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How to meet BS8102 easily.
BS 8102 : 2022 emphasises:
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One method of waterproofing continuous from the basement slab to above outside ground level. For a new build basement for a dwelling the only option is waterproof reinforced concrete.
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Important works, particularly the concreting, supervised.
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The structure should stop water getting in.
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A second defence would be wise, especially if it works differently.
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Note. An internal drainage system is not a waterproofing measure. It is NOT a second defence.
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Note also, BS8102:2022 does not allow any internal drainage system (because it does not allow the basement structure to be covered with anything) before all leaks have been repaired as fully as possible. If any water is still getting in then only seepage is permitted. More than seepage and repairs must continue before the structure is covered.
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My point on this page is that you should build properly and meet BS8102:2022 by achieving a fully dry basement from waterproof reinforced concrete alone.
THEN, BUT ONLY THEN, you could install a very small but obviously adequate internal drainage system with a shallow tray cast in the floor concrete as the sump. Probably close to your water heater in a plant room.
The solution is at the top of every page of this website. Continuous waterproof concrete to above outside ground level.
The second defence would often either be external drainage if it flows away by gravity, the example above, or else waterproof paint inside which I would use in the example below.
Please don't be confused by the different insulation, inside or outside. I have another page about that choice.
This page is about how a couple of hundred waterproof basements WERE built successfully.
This page is about what others do but you should avoid, what will be unsuccessful and leak.
This page lists the causes of leaks.
I have been building 100% waterproof basements for years.
Here the formwork of second hand scaffold boards is being stripped. The level of the ledge for outside brickwork and inside beam and block away from the basement changes as ground level changes.
You can see that the fibreglass threaded rods have been cut off outside already. They remain as a part of the concrete and will not leak.
The concrete will never crack because it was made with limited water, it will be a constant temperature against and under ground, it has additional steel precisely to prevent cracking.
The client is a farmer these days, but he had worked as a multi-skilled tradesman fitting out pubs previously.
He did almost everything single-handed except he sometimes had friends to help. One is a bricklayer with labourer building the rest of the house off footings, and another an electrician. The electrician helped tie steel and they all helped when concreting. I supervised all the waterproof concrete pours.
This next basement is also just getting the formwork stripped off.
A firm of agricultural engineers a few farms away dug the excavation, put in the land drainage and blinded the bottom with concrete.
I then took over and recruited a steel fixer who has worked with me from time to time for over 10 years. He does the work of 4 men on his own, so I only helped. The agricultural engineers sent 6 men to pour the 125m³ in the floor slab. I did have a few men from an agency but they were pretty useless. Toward the end there were only two us.
The house will be in the middle section with basement-level gardens at each end to give privacy from the footpath where I stood with my phone to take this picture.
The client has told me that between this and the house in the distance I will be building him another new basement in a year or two.
Where you see steel bars sticking up out of the walls, a few months after I took this photo I returned to bend those bars down and cast the ground floor over the basement. That's why you can just make out the fibreglass rods left sticking out near the top of the wall. They made forming the floor edge very simple and the waterproof joint very easy as well.
When this client sent me this next photo, he was providing me with a reference for another prospective client, and this is some of what he said.
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"we are very proud of the work Phil did for us and how he pulled the project together. The finished result is outstanding.
Phil has extensive experience and all of the civil engineering people we had on our development held Phil and his experience in high regard.
Phil has a very direct manner and gets things done.
Phil always without questions works in your favour.
Phil will save you a lot of money.
As you can see, I can’t speak highly enough of Phil and the work he does. He made such a difference on our development and we have been delighted with the end product. Our development actually sits in water so we needed every confidence we would have NO leaks. I have taken a picture of it today and attached it here. You can’t see the underground elements too well as they are below the water line
I have another house build on our current site that involves concrete near water and Phil will be doing that job too - he does not know this yet but he does now."
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This was the view in the other direction, from my bridge, when the basement was finished but before the steel frame and my return to cast the ground floor.
This client is firstly an artist and sculptor. Secondly he makes concrete worktops, in case you want one, and thirdly he does labouring and anything needs doing for a builder if he needs to earn more money.
Beyond the concrete pump just setting up is the workshop backed into a slope and it will have a studio above.
There is a lot of concrete below ground and a lot of hemp above ground here.
Higher up but still backed into the slope is his house with the ground floor largely buried and first floor above ground.
He did most of the work alone with some friends when concreting.
This client has a car workshop. MOTs, servicing and repairs. He recruited a team of Eastern Europeans who brought a few ideas of their own but he made sure they stuck to my rules. All went well.
This client has an engineering business. Lathes and drills and so on. He adapts gearboxes for people who want something a bit special. He built this with a bit of help from friends.
This client has a drain unblocking business. The basement is under the extension, which is full width and two windows back. Plus it is under the handrail. Part of the basement has a waterproof concrete roof. He built it mainly with a local labourer plus a few others on concreting days.
His son has bought a house in the village which he hopes to replace with a new house and basement. I am on stand by to go back and help.
This client has a timber business. He built this with some of his ex employees who were paid to help.
The basement is under the big area of glass from the front of the house to the back. Not huge. It is their kitchen.
All these basements, and many more, are completely waterproof from the reinforced concrete alone because all the concreting was supervised by me and I showed them how to avoid all the causes of leaks - so none of them repaired a leak either.
But what do you do to get belt and braces?
The house with the lake beside it has external drainage on the other 3 sides that discharges into a ditch, lower than the basement, about 100m away.
The others don't have anything else, but they could have:
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Bitumen paint all over the inside
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A tiny internal drainage system they install cheaply themselves.
Bitumen paint. Blackjack.
The instructions on the container will tell you to apply 3 coats brushing in different directions. I tell you to apply 9 coats.
Every coat needs to be very thin or else the surface of the paint dries before the paint beneath against the concrete dries or bonds. Once there is a skin, wet paint beneath will never dry.
You might have the surface fairly well covered after 5 coats but there will be tiny bits missing where a bubble in the paint popped, or where the surface is particularly rough. The remaining coats are finding and touching up these tiny imperfections.
Tiny internal drainage system.
The majority of basement floods in dwellings are caused by very poor workmanship when the structure was built and the pump or discharge pipework being unable to cope with all the water that leaks in over a long time.
It is therefore absolutely essential that the basement structure workforce believe there will be no pump and they WILL need to stop all leaks before they are paid in full.
They must not see internal drainage marked on any drawing or a big hole left by the excavation team.
The drawings might well say "shallow tray 600mm x 450mm x 50mm deep cast in the structural floor slab in the plant room to help mop up plumbing spills."
And, after
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The basement structure is complete
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After the whole structure is weathertight and the basement cleaned and dried, probably ventilated as well
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And after a period of heavy rain when all interested parties inspected and agree the basement did not leak
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And after the basement contractor had left for the last time
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Dimpled membrane could be fitted all over the walls and the floor and tiny electronics including a water level detector, alarm and small pump with a very thin discharge pipe could be installed to complete the internal drainage system.
If the basement never leaks and the pump never switches on, it will never break down.
BS8102:2022 is met in full before the drainage system not wanted by the Standard is added.
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