▽ +09.00Technical detail · PS-D-08
Foundation and raft edge
A membrane under the raft on blinding, protected by a screed, turned up a blockwork upstand that forms the raft edge and folded over its top, where the wall membrane laps onto it.
+01.00PS-D-08
Section and numbered callouts
Callouts
- 1Basement wallجدار القبو
- 2Lap with the wall membrane (L)تراكب مع غشاء الجدار (L)
- 3Protection boardلوح حماية
- 4Backfill compacted in layersردم مدكوك على طبقات
- 5Rendered blockwork upstand at the raft edge (permanent shutter)جدار بلوك مُليّس يشكّل حافة اللبشة (شدة دائمة)
- 6Membrane turned up the upstand and over its topالغشاء مرفوعًا على جدار البلوك ومثنيًّا فوق رأسه
- 7Fillet in the angle at the raft edgeفيليه في الزاوية عند حافة اللبشة
- 8Reinforced concrete raftاللبشة الخرسانية
- 9Protection screed over the membraneصبة حماية فوق الغشاء
- 10Membrane under the raftغشاء العزل تحت اللبشة
- 11Primerبرايمر
- 12Blinding concreteخرسانة النظافة
- 13Compacted subgradeتربة التأسيس المدكوكة
+02.00About this detail
What this detail solves
Foundations below the water table or in damp ground need one continuous membrane from under the raft up to the walls. A rendered blockwork upstand built on the blinding forms the raft edge as a permanent shutter; the membrane is laid on the primed blinding, turned up the inner face of the upstand over a fillet and folded over its top, then protected by a screed before the steel fixing and the pour. Once the wall is cast, the wall membrane laps over the folded edge on the upstand — the continuity of that lap is what closes the tanked box.
Critical points
- Blinding level, clean and as dry as the membrane requires, with fillets at the angles.
- Place the protection screed over the membrane before the reinforcement goes in.
- Protect the edge folded over the upstand until the wall membrane laps onto it by L, per the manufacturer.
- Groundwater level and expected pressure decide the system and grade of protection; BS 8102 classifies the protection types for below-ground structures.
- Never puncture the membrane with pins or bar chairs; use chairs with bases that sit on the protection screed.
Notation in this drawing
- Llap or overlap length, per manufacturer
- GWLgroundwater level
- NTSnot to scale
+03.00Downloads
Detail files
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Detail sheet — PDF (A3 landscape, Arabic & English)
Typical detailAR · ENR02026-10-08341 KB
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+04.00Related
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