French doors - what do I do with the inside cavity?

I've been abanded by a builder and am now finishing off the work to a new extension.

I've had some french doors fitted, sitting on a couple of blocks of wood on the outside of the brick wall cavity. The cavity is empty and the inside wall is the height of the concrete floor. I've got a wooden floor being fitted soon, but what do I do about the cavity...does the floor just go over the cavity up to the door? Also, what do I do about the blocks of wood that are supporting the frame? Do i just pull these out and fill with concrete underneath, as I can move them but then you cannot put any weight on the frame?

Thanks

GandK said:

I've been abanded by a builder and am now finishing off the work to a new extension.

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Did your builder do the necessary building submission notice for the extension to LABC or did he leave that to you? Have you had any inspections during the building works?

GandK said:

I've had some french doors fitted, sitting on a couple of blocks of wood on the outside of the brick wall cavity.

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Unless the installation is carried out by a FENSA registered installer who supplies a compliance certificate you are supposed to notify you LABC who will want to inspect & ensure it complies with Building Regs. before they will issue a completion certificate for your extension. If you cant provide a compliance certificate & it's not been notified or inspected, LABC will not issue a completion certificate for your extension!

GandK said:

The cavity is empty and the inside wall is the height of the concrete floor. I've got a wooden floor being fitted soon, but what do I do about the cavity...does the floor just go over the cavity up to the door?

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Are you referring to the cavity at the sides or in the floor where the door is? Current building regulations require cavity insulation so the rest of the cavity shouldn’t be empty! The floor cavity should be closed as detailed below.

GandK said:

Also, what do I do about the blocks of wood that are supporting the frame? Do i just pull these out and fill with concrete underneath, as I can move them but then you cannot put any weight on the frame?

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The blocks of wood have to come out & a brick course should have been built up to support the door frame at the bottom before it went in; a suitable damp course or membrane must also be installed below to prevent damp rising through in to the floor, the cavity closed & the internal floor screed should finished up to the frame. Don’t fit the wooden floor until you have all this sorted out!

Hi Richard,

Thanks for your swift reply.

Yes I submitted the bilding notice and the building control have been round a few times as required.

The cavity is filled with insulation from ground level up, but as you look at the french doors, you can see the empty cavity beneath.

Their is a brick course to support the door frame, but as its sitting on a couple of wooden blocks to keep the frame square, there is a gap at the bottom of about 15mm
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From your reply, it seems you’ve at least had some inspections so I don’t think you have any real problems to worry about but you need to take care of what’s remaining to get that all important "completion certificate". At the end of the day, if you don’t understand the required procedures, my immediate advice would be to contact your LABC, tell them what’s happened & ask their advice on how best to proceed; if you don’t follow procedure there is a very real risk you won’t get it signed off.

Concerning the door, are you saying the wood bits are only 15mm packers? can you post a photo?

Incidentally, why did your builder do a runner?

I've attached some pictures.

We agreed to end the contract as I wasn't happy with him working 3 hours a week for weeks in a row. There was a oak floor that was actually laid on top of what you can see, but the floor began to riase up and I have had to take the floor up....so we are now arguing over how much money I owe him!!

I think this is what I need to buy to fill the cavity:

http://www.screwfix.com/prods/70960...M;jsessionid=SGTSFEQUYPOO2CSTHZPCFFI?ts=84768

I don't think you really need the closer; looking at the photos, it seems you have a damp membrane in place under the floor, does the white bit of what looks like plastic go under the floor screed? Is the top of those bricks also the level of the DPC? If so, the builder should have left the plastic DPC in place under the door, is it there? Or is the DPC one brick lower?

Yes the white plastic membrane actually goes under the concrete floor (building control required I had this as we live near a dis-used landfill that emitts a gas, so we have vents underneath the plastic to let the gas escape).

The top of the bricks is the level of th dpc, although there is no dpc where the door has been fitted. You can just see where the dpc has been torn of on the left hand-side of the door.

is this ok? I was thinking of putting the closer underneath the white membrane, so the floor can go on top.

You need to replace the length of DPC under the door; it should never have been removed. Overlap what’s left of the original if you can, if not curl the ends up to the underside of the frame either side. Fit the cavity closer so the outer lip is over the top of the DPC; or instead of the cavity closer, you could put a lump of polystyrene into the cavity & cover the lot with a piece of damp proof membrane. Lay a concrete mix over the lot so that the top of the concrete is level with the under side of the polythene membrane; you will need to force the concrete under the door & point the outside, be careful not to displace the DPC.

Once this has dried, cover it with the white polythene & bring the edges up inside the door & skirting if there is enough spare; if it’s not big enough lay another piece of damp membrane over the whole area & bring this up inside the door & skirting. Finally cover the lot with a concrete screed mix so it’s flat & level with the existing floor. When it’s dry, cut off the excess polythene flush with the screed.

It should have been done with the rest of the floor before the door was fitted & the door frame would then be bedded on silicone. You don’t have much choice now & the screed may be a bit thin but it should be OK Once you get the floor down; don’t lay the timber flooring until it’s thoroughly dried out or it will warp.

Richard has pretty much summed it up.
But just out of interest I have never been asked by BC for a FENSA certificate, I think most of them realise it isn't really worth the paper it is written on.I have seen some shocking fits done by supposedly FENSA registered companies.

chappers said:

Richard has pretty much summed it up.
But just out of interest I have never been asked by BC for a FENSA certificate, I think most of them realise it isn't really worth the paper it is written on.I have seen some shocking fits done by supposedly FENSA registered companies.

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Absolutely, it really isnn't worth ****e; don’t get me wrong, I think the whole “self certifying” for ALL of the trades is a total cop out as far as LABC is concerned. It’s not supervised properly & is just a licence for many of the unscrupulous (licensed or not) to print money. Personally, I don’t trust any of them until they earn it. But have you ever been in the position of selling a property recently & been asked to provide the necessary documentation? If your LABC will issue a completion cert on what you present to them then fine but you should do as much as you can to avoid the risk of getting caught out. At the end of the day, it’s the completion certificate you need!