You are here: Basement Waterproofing Using Cavity Drain Membrane

OK, first I would like to thank you all for inviting me hear today, my name is David Symes and I’m the Technical manager for Delta Membranes here in the UK.

So if we are all good to go, we will have a forty minute expose on structural Waterproofing, and can I just say that during the course of the presentation, if any one would like to talk about and successes or failures you have had in the past, any techniques you have used and would like to explore, please feel free to stop me.

Firstly, a bit about me, I have been in the waterproofing business for about twenty years and my experience is in designing type A, B and C components in a structure in order to get the right degree of water tightness required on a job.

So we will start of by looking at BS8102, 1990, entitled the protection of structures against water from the adjacent ground, this is a riveting forty page document, you will be pleased however to note that we are only going to be looking at sections of the today, Its the guide book for anyone touching anything below the ground. We will be looking at Cavity drain membranes and making comparisons with traditional wet systems, most of which we will be doing through case studies. Also things have moved on slightly with regard to waterproofing legislation, things you guys need to be aware of as designers when you are out there in the field talking to clients.

So we will look at the British standard,
On the subject of BS8102, these are just a few interesting points that I like to make known to you.  From sect 2 Design & Structure – Para 3.11, it tells us that almost all basement structures are likely to be subject to water pressure at some period of their life. So even when basements that appear to be dry, according to BS8102, the design should mean that we should assume that at some point the water is going to come to bear on the structure and when it does, we have to decide if the system is going to cope with that eventuality.
Para 3.13 referring to existing buildings.  It tells us that when consideration is being given to waterproofing an existing building, most of the foregoing applies in some degree.  Additionally however, the condition of the structural elements and their ability to withstand the possible increase in head of water resulting from the waterproofing, together with the ability of any surface to accept the waterproofing treatment has to be investigated.  Now this is quite important.
As we know, water has 2.2 times the density of concrete.  As water rises around the building, we do have flotation forces in the floors, bending stresses in the walls.  If we apply a coating, we than create dynamic forces.  The water can no longer equalise into that space, so we have to decide that if we are using a coating or anything that is going to contain the water within the structure, we have to decide whether the structure has the ability to cope.
Now that doesn’t apply to a cavity membrane system. The reason that it doesn’t apply to the cavity membrane system is as the water comes to bear on the structure, as it builds up around the structure, we are not really changing anything.  We are allowing the water to ingress.  It will run down behind the cavity created behind the membrane, we will then take the water to a pre-determined drainage point, at which point it will be evacuated away from the structure, which will be shown later.

On water tables para 3.4 structural considerations.  BS8102 states that basements not exceeding a depth of 4m, a design head of ground water  ¾ of the full depth below ground is usually adequate, so basically what we are looking at is a basement 2m deep, has to be designed to cope with a 1.5m head of water.  It goes on from there, further for deeper basements, the water table should be taken as being 1m below ground level, so for a 6m deep basement, we have to design it to have a 5m head.
BS8102 also refers to 3 different types of tanking.

  • Type A being tanked protection.
  • Type B being structural integral protection.
  • Type C being drained protection.

What we are offering here is basically a preformed type C. Now interestingly, it does state hereon BS8102, for those seeking maximum assurance, (referring to type C drained protection), this combination of construction and waterproofing is considered the most effective and trouble free.  All point are highlighted in this copy of BS8102, which is available for inspection at the end of the talk.
I just want to touch on BS8102 (1990).  BS8102 is the code of practice for the protection of structures  against water from the ground.  BS8102 is obviously all encompassing, including external and internal refurbishment situations. 

This is an extract, which shows table 1.  Table 1 is a guide to the level of protection to suit basement use.  It is split into 4 grades.

  • Grade 1 is for car parking and plant rooms excluding electrical equipment workshops, which says that some seepage and damp patches are tolerable in new construction, Basically a concrete box with water bars.
  • Grade 2 is for workshops and plant rooms requiring a drier environment and retail storage areas.  No water penetration, but moisture vapour is tolerable. If we look at dense renders, migratory crystalline slurry type systems, whilst they are waterproof, they are not vapour proof so allow the transmission of vapour through them.
  • Grades 3 and 4 are looking at ventilated residential and working areas, including offices and restaurants etc.  or archives or stores requiring a controlled environment.  BS8102 suggests that water vapour is no longer tolerable.  What we offer you here with the cavity membrane system is something that is not only waterproof but is vapour proof as well.  Also cavity membrane systems can be used in anything from grades 1 to 4.

Any questions on BS8102?
Starting off above ground, this was not a waterproofing application but damproofing in Suffolk.  It was previously an agricultural barn, purchased and upgraded for residential occupation.  A building survey had indicated that it had all the typical problems, defective roof covering, no real rainwater disposal goods to talk of, porous brickwork and also internal contamination – uric acid from the cows, nitrate salts and chloride salts.  Also as you can see, substantial thickness of walls.  According to BRE (Building Research Establishment), they tell us that once all defects are rectified and a chemical damp-proof course has been installed 150mm above the highest solid oversight in accordance with BS6576, they tell us that we can expect the structure to dry out at a rate of 1” per month of the thickness.  So you can well imagine that even once we have waterproofed and damp-proofed this building, it will still take a couple of years drying out.  So what we have here is a sympathetic solution.  We come along with the mesh variety of membrane; it is actually secured to the wall with those special sealed fixings.  We utilise a  ventilation profile, with a spec ventilation detail that we have that allows air movement behind the system. This really means that we are not inhibiting the drying out process in the wall, we are isolating those aggressive salts.  If you can imagine it with a direct applied render or direct applied plaster, the salts can effect those coatings, but the membrane,  being inert, has a compatibility with those problematic contaminates and it does give us a barrier.
The membrane is fixed at 250mm centres.  We come along with the plaster dabs or dry wall adhesive.   We actually support the plasterboard temporarily with a baton or wedges from below, then we squeeze the plasterboard onto the dabs.  Once that is done, we apply scrim tape to the joints, give a 3mm skin of plaster and within just a few days we can actually decorate.  When I say decorate, we can even use vinyl-based paper or vinyl paints.  We only have to wait for the 3mm skim to dry out.  So the emphasis is also on a very fast track system.

This is the Royal and Derngate theatre in Northampton; it was sponsored by the English heritage in conjunction with Northampton Borough council.
An Architect called in a company to identify a tanking system.  Here we had stalls and stage areas some three metres below ground, the company had recommended a dense conventional type system. With buildings, we consider that structures are live; therefore if we have a wall that is tanked and the structure moves, the tanking will fail.
What we have done here is come along with our meshed membrane, this shot shows detailing around corners, this shot shows our non meshed membrane, here we have used this because of the extent of services at this point, there was a drain placed along the base of the wall, our Delta channel, that takes the water away to an evacuation point.
This shot shows our meshed membrane, this is lime putty plaster applied to it to show we can use directly applied plasters.
Going underground, this slide here shows the Royal Bank of Scotland, Tottenham Court Rd.  We had a problem here with water ingressing through the pavement lights and also through the front elevation.  Nothing that we could do with the lights, so a specialist company was employed who removed, resealed and replaced them, but there was a problem of water ingressing through the front elevation.  What we did here was to apply the membrane across the walls and we took it across the floor.  There was an existing drain, which was surveyed and found to be suitable for the purpose of evacuating the water away.
A freestanding frame was put in front of the membrane because the wall was undulating quite a lot, and a 50mm screed was put over the membrane on the floor.  This allows the water to still ingress through, it runs behind the system, we pick it up with a channel that we created within the floor, it goes to the drain and is evacuated away.  Now when doing limited waterproofing like that, if you can imagine again I will take you back to the use of conventional systems.  If you put conventional coating on there, what you are doing effectively is holding the water or damming it up.  We are letting it in, controlling it at source and we can give long-term results without moving the water to another part of the building, which is currently unaffected.

This is a shot that I always show, reminding me to remind you of the downside of cavity membranes.  Whilst I am here to extol the virtues and benefits of the cavity membrane system, it is true to say that waterproofing is horses for courses.  Installers do not just have the Delta system at their disposal, but other ranges of waterproofing mediums for use in various given situations.
A flat soffit, the example being shown here is a good example of where not to use cavity membranes.  Because it is an external soffit that extends under the roadway or pavement, open to the elements, water can and will pond behind it.  When water ponds behind it, it puts pressure on our fixings and we can have a failure.  So what we do is use an alternative.  I will contradict myself here, as the slide shows a good sloping soffit, which meant that we could run the water away.  There is no problem with vaulted soffits, but it is external flat soffits that are subject to water penetration, that we tend to avoid with cavity membrane systems.

This example, Comedy Store, Leicester Square.  Westminster Council were threatening closure.  This was an area for storing wine and food products, which the council felt, was not fit for the purpose.  They needed a very quick and obviously reliable solution.  What we did was took the electrics, consumer unit etc. and made a temporary frame.  Applied it to the temporary frame, lined walls and floors with our membrane.  The plasterboard was put up, it was decorated inside and out, the joints were taped, it was given 2 coats of emulsion and they were back in business within 2 days.
Under street vaults.  Under street vaults are a feature of many city centre areas.  They were constructed generally in a by-gone era, usually for the storage of solid fuel.  Typically speaking, when you go into any or these vaults, you will usually find a circular hole that leads up to a cap, which used to be sited in the pavement.  Coalmen would come along, lift the cap and pour the coal into the vault. The coal was then consumed by the dwelling.  The intended purpose of the vaults is now defunct, as we all have central heating either gas or storage heaters.  Many of these vaults are sited in city centre areas where property values are high and are very much usable space.  Vaults come with their own set of problems.  Firstly they extend under pavements adjacent to or even sometimes under roadways, so we have the problem of vibration.  Also when vaults were constructed, the vault was constructed and the front and rear walls were made out of an infill and not tied into the vaulted structure, so we have a natural movement point.  Now if we apply a dense coating that is essentially brittle, the first hint of vibration, or the first time a dustcart or skip lorry comes along, we can and do get failures.

The benefit of a cavity membrane system is that we have an elongation break greater than 50%.  This means that we can cope with any amount of vibration and even small amounts of structural movement, which does give us a distinct benefit wherever vibration or movement is evident or expected.  If we’re going to have enough movement to cause the membrane system to break down, it’s really time to call in the engineers and restabilise the structure.  It’s not really so much of a waterproofing issue.
Here we see how membranes are detailed around a vault.  As I said earlier, we overlap it like slates on the roof, so whilst we have a nice seal in place, we don’t actually have to rely on it.  On this occasion, the fixings were put in at 400 centres, ready to accept battens in future, but the area was upgraded to a dry storage area, so we applied screed over the floor and left the wall membranes exposed.
This one is in Grantham, a basement with something akin to a stream running through it.  We had no structural integrity in the slab, so the slab was replaced.  We utilised the temporary drainage system, incorporated a new mechanical drainage system into this one and as you can see we have gone from a previously unusable space to something that is used as a bedroom area.
This needed a lot of personal attention for obvious reasons.

This is the Connaught Arms in Portsmouth.  This had an asphalt tanking system.  Asphalt had been applied to walls and floors on the negative side.  As we all know, these products don’t work unless loaded.  Here you can see that the asphalt should have had a loading slab over it and as far as the walls were concerned, we should have had concrete block walls constructed in front of it, then the cavity filled and vibrated to actually hold the asphalt in place.  It was no surprise when water started to ingress at the base and ingress at the wall/floor joint.
Whitbread the brewers had already spent once to have this done and wanted a product that was a) effective   and b) cost effective as they were having to spend out for a second time. We had been recommended by a local Architect.  The benefit of the membrane system was that we could leave the old asphalt in place. We applied membrane to the walls and floors.  Here we see the area where the draymen drop the barrels into the cellar, so instead of the normal 50mm screed, a 150mm re-inforced concrete slab was placed over the membrane to give the barrels something substantial to land on.  Down the sides of the walls we put marine ply, for we did not want to plaster these areas, otherwise  the barrels would take it odd in time.
We utilise mechanical drainage here.  There was an existing sump.  Typically in domestic situations, if there is mechanical drainage, all pipework and everything is hidden, but Whitbread were not bothered about this, as was just wanted a functional area, so the drainage detail features are left showing.
This is the before and after of the job, but this shot does tell a story.  In the top right hand corner of both pictures, you can see a cooler unit.  Whitbread would not allow it to be moved, as it would disrupt the operation of the pub above.  We had to put in a caveat in the report saying that whilst we whilst we couldn’t afford the cooler with any protection, we couldn’t guarantee that it wouldn’t rot away in time, bearing in mind that it had a steel casing and was adjacent to a very wet wall.  We have applied membrane around the cooler unit.  Now really the benefit of cavity membrane is not building up any pressure, not damming or holding the moisture.  The thing here is not trying to hide the problem.  We’re not pretending the moisture is not there, we’re letting it in. We’re not going to divert it and give the cooler unit a problem, so whilst we had to put the caveat in the report to state that we wouldn’t create a problem, if it rots away in time, so be it.

This is Kensington Palace, one of the royal households.  Here we had a situation where we had to put a drainage system in. At the top you can see a temporary pump.  The temporary pump is taking the water away from that channel, giving us the ability actually to excavate.  Here you can see the channel filling up with water in the winter months.  Within the space of ½ hour, the channel will fill up.  The basement is on two levels, the lower level fills with 150mm (6”) water over the course of a weekend.  This area was known as Kings Kitchen but is now known as apartment four.  Here we put drainage system in.  Firstly, we put a geo-textile into the though.  We then put in on this occasion, a 150mm perforated pipe and surrounded it with pea shingle.  Take no notice of the red pipe, that is a temporary pump working further down the line.  We then folded geo-textile over and screeded it back into position.  The water no longer enters at the weak spot, the wall/floor junction.  It enters directly into our drainage system.  We were working closely here with a geo technical engineer.  The water when it reaches our pipe comes in through perforations, goes on its journey to the sump area.  When it gets to the sump, there are two float-activated pumps that work on a duty standby basis.  They are backed up with an alarm and a battery back up, just in case of power failure.
We were working very closely with English Heritage's Structural Engineer.  This shows the upper level.  Now English Heritage likes our system.  They like it for two reasons, they see it as sympathetic to traditional structures and they see it as a reversible process.  They like the idea, that they can come along in five, ten or even one hundred years time, they can remove it and you can find the original fabric.  They don’t like systems where you have to utilise destructive preparation techniques either.  Now these are a good couple of examples.  The quarry tiled floor, again believe it or not, they wanted to keep it, so what we have done here is to apply the membrane over the quarry tiles.  We’ve laid 25mm expanded polystyrene jablite material, then an 18mm floating tongue and groove chipboard flooring.  That’s the make up of the floor.
Around the firebreast, there was an Aga in there.  The Aga was sent away by Prince Charles to be restored.  We don’t know where it went, but it has not returned to the building.  Again around the firebreast were tiles, old Victorian we guess, all crazed and cracked.  Again English Heritage wanted to keep these tiles in their historic building.  That’s something we’ve accommodated for them and put the membrane over the top of the tiles.  The idea being that they can take it off in the future and find the original tiles.  But that does again tell a story.  If we look at most direct applied systems, we rely generally on the integrity of the structure, when applying them.  A lot of failures occur, not because the systems don’t work, but usually because the preparation has not been carried out adequately.  So we are removing the biggest area of potential failure which is inadequate preparation.
This area is under the Prince of Wales courtyard.  You can see where the membrane has been applied to the soffit, and down the walls.  It has already been applied across the floor, screed has been laid and we are waiting for the plasterboard to be applied.  The benefit here of the system and having battens is that we’ve a space to run wiring through and conduits etc, so it makes it very convenient for lights, sockets etc.  On this occasion they put lots of CCTV wiring and such through.

This is from the job in Newbury.  Here we had water ingressing.  Typically speaking, what we do with the system is to ensure that the water on the slab won’t build up any more than the stud height of the membrane, before it equalises into our drainage system.  So we use a very complicated piece of equipment quite often on the smaller sites, which is that piece of hosepipe and carry out a flood test.  Obviously, we ensure that the water can’t pond any more than the stud height and if it does, we create channels i.e. least line of resistance for the water to pick up with our drainage.  Even if we have a wall such as this, which will cause a bunging effect, we cut through it to release the water.
We have various ways of controlling water.  In the case of the house built into a hillside, for example we’ll use the open elevation to discharge the water.  If we have existing serviceable drainage, we’ll utilise that.  If we have no other way of removing water, we’ll use mechanical drainage.
This is a shot of our pumps, these are installed in our chambers and typically work on a duty assist basis, one of these will typically discharge 120 litres a minute, this will double if the other unit kicks in.
This is a single pump and this one is one of a dual chambers
Here as you can see, a dual system.  These work off a panel on a duty standby basis or double duty if required.
We do also utilise foul chambers for retrofit basements.  For new basements that we are creating, especially in London, to take sewerage etc away, as long as we use the appropriate pipe work.
This is our battery back up unit, this will typically pump 8000 litres of water in back-up mode, it looks like something from the computer industry, because it is. This is a battery, anti-surge protection unit and charger all in one, you can add additional batteries to these which will provide another 20,000 litres.
These units can also be fitted with SMS text diallers which will dial up to eight mobile phones to tell you your basement is flooding when you are lying on the beach somewhere.

This is our alarm panels.
Here is a typical application.  We dig a hole, we drop the tank into the excavation.  We always ensure that we fill the tank with water, for although it appears to be dry, there have been many occasions when we come back next morning and it has filled up overnight. The concrete has banked around the tank and the tank is sitting 2ft out of the ground.  So we tend to fill the tank with water before we concrete around it.
Here you can see a couple of connections that have been made into the Baufix 200 tank.
We have a range of channels, this is our Delta channel, these can be rebated into the floor or we also use these in new build jobs that have failed, we site them on the existing floor and run a modified screed incorporating an SBR, styrene butadiene resin. This is showing detailing around internal and external corners.

We also have a perforated pipe with a finds control layer.
Back water valves, we have these at our disposal, this has two flaps in it, in the event the first flap fails to close, we have a second flap, a double indemnity valve.
This is an electronic version, this will close off, the macerator will take the waste and inject it through the flap, it will work against a charged system, ideal for the occupant that can continue to use the services, a self contained basement flat for example.
Moving onto railway arches.  We do lots of railway arches.  Railtrack have realised that they have lots of usable space.  These arches are quite often sited in a lot of very expensive city centre areas.  Before they are upgraded, they are really suitable only for low-tech businesses – scrap metal dealers, back street dealers etc.  Once upgraded, it is very much usable space.
This is a case of point.  This is a very good example.  This one is in Birmingham.  This building is known as Musical Exchange.  Here you see the membrane has been applied, the battens are secured into those special sealed fixings, the plasterboard is then applied, the joints are skimmed and here we have the finished result with the building being used.
Here you can see that we have gone from something that was wet and unusable space to something that is used for storing sensitive, electronic equipment.

Ok, so we start off with our new build basement, we excavate our hole and in this instance, the hole has been made for one of our sumps, when the floor has been cast, the tops of the pipes are cut off and the membrane is laid across the floor area.
This is one of our sump chambers overlaid with screed and Delta MS20.
We can pick up light wells with our sumps no problem.
So this is a load bearing wall internally, these engineering bricks you will note have open perp joints, oversized dpc will be dressed over these and seal each side to our membrane thus providing that vapour seal and detail.
So we have our basement, MS500 is used on the inside here and this is the primary waterproofing used externally, a product called profi-tight, this is the primary waterproofing, this is applied first coat with a notch trowel for the thickness and the second coat with a flat trowel
This is featuring Geo-drain.  The Delta Geo-drain is applied on the positive side.  It is a 3-layer product.  The 1st layer is a slip membrane.  The slip membrane goes against the structure.  The purpose of the slip is when we back fill against this it allows it to actually slide without chafing.  Think of it as a lubricant.  We then have a studded structure that faces the backfill and then the geo-textile.  The geo-textile allows water to enter the cavity, whilst keeping the fines (very small particles) back in the soil.  We can then take the water down to the perforated pipe, a drain for example.  Essentially, what we have here is a protection board, a drainage system and a waterproof layer all in one.

Now, when we look at buildings, should we waterproof them from inside or outside, well it is our view that we should do both, the reason for this is firstly, the building is the first line of resistance and we will never have the ability to waterproof it again unless we excavate, but the problem with external waterproofing is that it is not accessible, not maintainable and not guarantee able.
Typical finish over one of our sump chambers.
Contiguous pilling, we get involved with a lot of these jobs as space is at a premium, this is a job in Chigwell, we attach the membrane to the walls, these take wall ties and the internal skin can be constructed.
Here you can see how we have overcome a squint bay using our various seals, we can cope with more or less any shape.
There’s the finished article.
Here you can see sealing round the service entries.  Now, service entries and conventional systems, are seen as a problem.  It’s not a problem with the cavity membrane for 2 reasons.  Firstly, ingressing water coming in at the service area, once it picks up at the cavity, gravity takes over and we can then pick it up with our drainage system.  But also our range of sealers allows us to create a good, effective, efficient seal around them.
I mentioned flat soffits earlier, but we can cope with doorheads, as we can get sufficient fixings into the doorhead to ensure that no significant ponding occurs.  Here you can see this one is in the University of London.  This is a very deep, sub, sub, sub basement.  We have used MS20 on floors.  The MS20 gives us much better draining capacity.
Here you can see the membrane has been sandwiched between 2 structural slabs.  This is a real typical type C application.   The product will take loadings of 250 k/N per m², 25 tonnes per m².  But when the studs are filled with screed or concrete, once the concrete has gone off, we do get load transfer down into the base below and these loadings go up 10 fold.
Here you can see the wall/floor joint, where we are fixing clear 8mm membrane to 20mm membrane.  The reason that we have clear membrane is so that when fixing to walls we can get good fixing points.  That is important when dealing with friable brickwork or random stone, or such like.

London Underground Stations.  The system is generally specified and used on the London Underground system.  Those London Underground stations, when they were constructed, were constructed above the level of the then water table.  The water table in London was considered for many decades to be static.  The reason we have a rising water table in London, I know that a lot of people have put emphasis to climatic change, but according to CIRIA its due to industry.  Or should I say lack of abstraction, that industry used to undertake.  We had a lot of heavy industry in and around the London area and it used to take water from its own wells to service its needs.  A lot o industry is closed down, moved to 3rd world countries or moved to green field sites out of London for cheaper rent/rates.  As water is no longer being abstracted, we have a rising water table.  So those stations that were constructed above the level of the water table, many of them are now surrounded by the water table.
Here you can see where a hole has been drilled and water is running down.  Here you can see a blister.  The reason it appears to be black, is because that is on the trackside, the brake dust of the trains tends to cling to any surface that is uneven.  That’s actually a slurry product that has bubbled up.
This one here is from another station.  Here you can see those deposits.  Typically speaking, those deposits can build up, but when we apply membrane, what we look to do also is to stop the process of evaporation, because the minerals come through in solution.  So if we stop the process of evaporation, it means that those minerals then come through in solution, continue to remain in the solution, so that stops the system getting clogged up.
Here you can see membrane applied at 250mm centres.  Here you can see we’ve used a product called Tilcon Whitewall.  The Tilcon whitewall is high inpact plaster.  We push it into mesh.  The 1st coat is to bond the system together.  We then scratch it up to create a key for the subsequent coat.  The next day we then apply 2nd coat and that’s trowelled up to a finish.  There are various different finished applied thereafter over the top.  They can range from poster panels, signs, ceramic tiles and sometimes even vitreous enamel tiles
Here you can see the 2nd coat being applied and you can just about see the scratch coat in the top picture.
We do have other problems with London Underground sites.  That is accelerated drying.  There is lots of movement of air through those tunnels and again if we look at cement based systems, we’re usually trying to decelerate the drying time, trying to keep it wet for as long as possible.  With a cavity membrane there are no detrimental effects and whilst the finish dries out very quickly, there’s no detrimental to the integrity of the system and its ability to do job as cavity drainage membrane.
London Underground have tried all kinds of methods.  One they find to work is grouting, cementious or resin grouts.  They find the leak, come along with a team, drill through and fill up with grout.  They find that it works as it seals up the leak, only to find in a couple of weeks that it diverts down the station.  So London Underground now use these systems as what they call a water management system. The water is diverted down into culverts under the station, where pumps are sited and those pumps actually then lifts the water out of station.  But as far as the client, the travelling public is concerned, all they see is nice dry and clean surfaces.
Here you can see a station where the membrane has been applied in readiness for plastering.  Typically speaking, although this station was actually closed down, because of fire regulations, what we normally do is we put as much membrane as we can up at night, usually starting at 1am when the station closes down.  We put up as much as we can and give it 1 coat of plaster on the same night to give it a fire rating.  On the overlap we put zero rated ply.  The next night we come down, remove the zero rated ply on the joint and then carry on.
Going back to the railway arches, you can see here that using clear membrane, we’ve put it up like slates on a roof and you can normally see every brick.
This is using PT externally.  The Delta PT is ventilated up under the soffit.  We then take it down to the bell drip and it means that when we are using on the outside of a building in an above ground situation, further moisture penetration isn’t possible, but we still allow the building to dry out.  Another benefit you get in using the system is a reduction in U values.  The cavity created by the membrane gives reduction in U values, which again is a benefit in insulation.
This is a render that is made to look like brickwork.  Here, those panels are a white render. This when it is done never needs painting, just washing every so often.  You can make it look like stone or you can have whatever colour you like.  Recently we did a Sikh temple in Southall and put an orange band round the top of the building, because this shade of orange had a particular religious significance. The only shades that cannot be created are blue shades.

That’s the front of the Kodak building.  Nothing was done to the front façade, all work was done to the rear of the building.
Here is a table of chemical resistance.  If anyone is unlucky enough to run out of petrol on the way home and you take a plastic can into the petrol station they will refuse to fill it up. However, they will sell you a can made from a special type of plastic and that’s what these products are manufactured from.  So you can also use it where there is contamination.
This is a very special guarantee.  What we call a pathway guarantee.  Reason that we call it pathway is because once down the pathway, you’ll never see us again.  Seriously, it’s a 30-year product guarantee, which covers product, seals and all the fixings.

We now do have current British Board of Agrément (BBA) approval.  The BBA states here that under the terms of durability, it says that under normal terms of use, the system will provide an effective barrier to the transmission of salts, liquid water and water vapour for the lifetime of the structure, in which it is incorporated.  Again copies of the BBA is available in the literature pack.
People say that it is only a piece of plastic.  It is only a piece of plastic.  It has been put through accelerated ageing tests against our competitors.  As required in Sweden you have to prove that the product will last for 50 years.  Our product after the accelerated ageing tests to Swedish standards was still intact, some of our competitors’ products didn’t fare so well.  I won’t mention any brand names.
Moving on, we have a whole section of detailed drawings, showing how the system goes together.  Shows the mechanics of the system, how and where it is used.  This is available in hard copy and can also be downloaded from our website.  Thirdly we also have it available on AutoCAD disc.

David Symes, Technical Manager, Delta Membrane Systems Ltd.
Bassett Business Centre, Hurricane Way, North Weald, Epping, Essex, CM16 6AA.
Tel: 01992 523 811.  Mob: 07810 562 987.

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