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self build basement concrete waterproof self build basement formwork shuttering wall form self build basement drainage membrane self build basement concrete waterproof consultancy self build basement concrete waterproof supervision training
Concrete additives to make your work easier and better Formwork accessories to make your results waterproof and flat Budget external drainage membrane Consultancy and advice On site supervision and training

 

External drainage membrane for basements.
For Sale.
Dimpled membrane £120 per roll. 20m x 1.9m (dimpled width 1.8m)
Filter membrane 4.5m wide £2.50 per linear metre.
Plus delivery and VAT.

External drainage membrane needs to be two layered
  1. filter membrane facing the soil

  2. dimpled membrane that allows the water to flow down to the land drain at the bottom
external drainage membrane basement drainage membrane

Good quality external drainage membrane has a flat edge one side only, so that overlapping is as simple as possible. A simple overlap means that one screw fixes both sheets.

External drainage membrane bobble edge External drainage membrane flat edge

You can see that it is for external use or else it would be rolled the other way.

External drainage is different to internal drainage because it is much thicker and tougher to withstand the weight of backfilled soil without the dimples collapsing.

If you find similar quality membrane cheaper elsewhere, we will beat the delivered price by 5%.


The flat side of the dimpled membrane is fixed to your concrete or insulation.

The filter membrane is fixed over it and folded over the top to allow only clean water to flow away.

With a bit of forethought this can be very easy. The external drainage membranes only need to be fixed until the backfill holds it all in place. When you cast your walls you could easily fix some small roofing batten inside the formwork so you have regular places to screw the external drainage membranes to the wall.

You must have a ground investigation that tells you whether your basement will sit beneath the water table at any time of year and what the soakaway characteristics of the ground beneath basement level are because, to succeed, your external drainage has to drain quickly under all circumstances.

It has to be installed well so that water gets into the system and away easily.

It has to be wrapped completely in filter membrane to keep out silt.

It ought to be roddable to keep the pipes clear.
  external drainage membrane to land drain



Vertical drainage membrane lets water flow easily down the outside of basement walls to the land drain around the slab.

Drainage may go down a slope to a ditch, which is virtually foolproof, but it usually has to go to a soakaway.

You do not want the soakaway overwhelmed by rain water because it will fill up and back up all around your basement walls before it can soak away.

You can help your basement drainage by sloping all the ground level surfaces away from the building and having wide eaves as well so that much less rain water will find its way down the side of your basement.

If your basement soakaway is only dealing with water from beside your basement it is more likely to cope. Have two soakaways opposite sides of your dwelling: one for basement water, the other for roof water. That way all the water falling on the roof, soaking away at a higher level than your basement water, should not find its way into your basement soakaway to overwhelm it.



In conclusion.

Always build the basement with waterproof concrete with me supervising so it is waterproof.

If external drainage works in your situation, use it.

Particularly tough, yet cheap.

Comparison table:
SelfBuildMyBasement Ltd Newton 410 Geodrain Wykamol Geotex Membrane
Colour and material Black HDPE Black HDPE Various. HDPE
Density 1,100g/m² 740g/m² 900g/m²
Material thickness 1mm 0.6mm
Stud depth 8mm 9.6mm 8mm


If you buy either Newton 410 or Wykamol Geotex, their instructions tell you to peel back the geotextile filter layer and overlap the studded plastic layers before overlapping the filter layers.

Both also sell you a plastic covering strip for the top to stop dirt getting down between the two layers.

It is so much easier, and usually much more effective, to put up the studded sheet first then to cover it in full-width (usually 4.5m) geotextile membrane, simply tucking it over the top to keep the dirt out from above and having plenty at the bottom to wrap over your land drain in one go.



external drainage membrane for basement

external drainage membrane


Our rolls are 20m long. The full width is 1.9m. The width with studs is 1.8m. The flat edge at the top means a small overlap to keep the water draining correctly is very simple to achieve - much easier than trying to match up studs in two different sheets.

Price £120 each plus delivery and VAT.

Please Note. You need to buy the filter membrane separately, for instance this. Keyline sell smaller packs as well.
From time to time we will have it in stock and you can ask us to include it with your order.







Call me, Phil Sacre:

01438 900303




07773 377087





Email me:

philsacre@basementexpert.co.uk

 

self build basement concrete waterproof self build basement formwork shuttering wall form self build basement drainage membrane self build basement concrete waterproof consultancy self build basement concrete waterproof supervision training
Concrete additives to make your work easier and better Formwork accessories to make your results waterproof and flat Budget external drainage membrane Consultancy and advice On site supervision and training
Home

SELF BUILD MY BASEMENT

Case studies