Extensions Question

Poor standard of brickwork on 4x3m extension.

I am in process of having a 4x3m kitchen extension on back of my house. The brickwork is aprox 5ft high on one side and aprox 2ft up on the other side. Builder has not been on site for a week as he is on holiday.
There is mortar missing from inside of brickwork and the bricks joining on to original house are not lined up but are up to 5cm lower. Also there are metal ties up the wall joining old build to new. Builder has not cut through to cavity of house for DPC, as stated in architect plans.
One of my biggest worries is that due to it being a land fill site in past, vents had to be put in at just above foundation level to release methane gas build up. but the polystyrene insulation slab and concrete base have shrunk revealing gaps in base to damp ground below. I need advice on how to proceed.
Up to now we have paid the builder £8000 [Not inc foundations]. We paid separately to a company to have foundations piled as building inspector said ground was unstable for normal foundations.

3 Answers

Not seeing your plans I would not like to advise you, but if I was you I would get the building inspector round. He will tell you all you need to know.

Answered 11th Aug 2012

C Whipp Construction

Member since 8 Feb 2012

If your building on or near a land fill you need a gas membrane not gas vents.Speak to you architect and check for contaminated land on your plans,should of been picked up by planning.Get building ins to check brickwork and floor.I cannot understand why things go wrong on a simple job.Get a tight hold on problems and deal with them asap.Cheapest way is right first time.Hope this helps you,I would if i could

Answered 17th Aug 2012

l.mcguinness building and joinery

Member since 10 Jul 2012

Hi, I would like to try to put your mind at rest. Building Control SHOULD have checked that the Gas/Damp proof Membrane was correctly installed with the vents before the slab was poured. They will tell you if they did. If they did then you are not looking down to damp ground but to the Membrane. The Shrinkage is a good thing, as when the building is eventually Dry and Warm, the slab has room to expand and not push out on the walls.
The miss alignment in the Brickwork is probably that they are now using Metric Bricks to a 75mm Gauge(the height of brick+bed) when the original is Imperial Bricks to a 3" Gauge.The minor difference is multiplied by each course causing the miss alignment.
It is possible to build Metric Bricks to Imperial Gauge but the resulting wall will not look as good or be as strong.
With respect to lapping the DPC into existing, they might have extended the DPC 1m up the wall behind the metal Starter Tie(which is how Building Control required it previously) If they Have done this Highlight it to Building Control at their next visit (Wall Plate, where the wall meets the roof) and they will make them change it(not too hard and not to panic about)
With regards to proceeding, I suggest you discuss your concerns calmly with your builder upon their return.
Best Wishes

Answered 17th Jan 2015

Stewart Building and Roofing

Member since 12 Dec 2014

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