Beam and block floor procedure

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Hi.

Can someone please tell me if the way I am fitting the floor is correct.

It is the first time that we have had to use beam and block.

1. Fit DPM over the earth thats below wall level to stop any vegetation growing.

2. Lay the beam and blocks.

3. Grout the area with a cement slurry.

4. Lay the radon barrier over the top and also form the cavity tray with it.

5. Lay insulation and finish floor material on top.

I also have an integrated garage, but due to this having a room above I'm assuming that the same procedure applies to that area as well.

Thanks.
 
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Don't forget the telescopic floor vents.

The radon barrier will indeed need to straddle the cavity. However, you will then need to tray the cavity at external dpc level back up the first course of blocks.

The cav tray will need to be higher internally so that water is deflected from inside to out.
 
Hi noseall.

I do have the telescopic vents, but forgot to mention them.

How does the cavity tray get formed with these fitted?

Cheers.
 
The cavity tray is formed at and above dpc. You would lap some 600mm damp onto the dpc layer then lap it up onto the first course of blocks of the internal leaf.

The telescopic vents are almost a mirror image of the above whereby they start at dpc and go down through the inner leaf that supports the floor beams and into the floor void.

However, looking at details of gas membranes (B&B floors), whereby the cavity needs to be closed off by the membrane you are correct in assuming it doubles up as the tray also.

I found this.

And this...which shows the vents passing through the membrane?????

DETAIL16-Model.jpg
 
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This is exactly how i described it in the previous post and is how we have done it in the past.

Doing it this way avoids confrontation with the tele vents.
 
The pic that you have posted has the Radon barrier laid on top of the beam and block floor and then forms directly into the cavity tray.

On the pic 3.1 that is shown on that link the Radon barrier is laid on the beam and block floor, but goes directly across the cavity.

The cavity tray is then formed above.

Doing it this way means that you don't have to cut the membrane around the vents. I have spoken with the BCO and he is happy for me to do it this way.

Am I getting this right or am I missing something. This is the first beam and block floor I have done.

Cheers.
 
As i have said (in two previous posts) fit the barrier so that it goes horizontally across the dpc then tray above. ;)
 
Hi noseall.

Sorry.

I just re-read from your first post.

I now see that you have explained what I was asking, but I was concentrating on the pic that you posted, which is showing the cavity tray being formed straight away.

I have seen the pic that you posted on a few sites, but it seems like a lot of hard work to do it that way.

Am I correct in saying that you would have to cut around the vents and then seal them in some way after.

When I first asked the BCO about the procedure he was adamant that I did it in the normal way, but after explaining this way to him he changed his mind.

I found it strange that he didn't know this way.

Cheers.
 
We have fitted a gas barrier to a conventional solid floor whereby the membrane was fitted as i described in my first post.

When trawling the net to find out about a gas membrane detail regards a B&B floor it came up with the detail showing the telescopic vents passing through the barrier, which i found a bit weird and fiddly hence my reluctance and question marks.

The importance of the membrane is to provide a seamless gas barrier over the whole site and puncturing it with telescopic vents at such a difficult junction (i.e difficult to seal) would be foolish.

Doing it the way i suggested, and as shown in the pdf figure that you provided, means that there is no interference from the vents below which simplifies the job somewhat.
 
P.S.

Don't be surprised by a B.C.O's lack of knowledge or their eagerness to nod when provided with a better solution.

Some are a bit wet behind the ears but a a good few are seasoned sharks so watch out! :p
 
Thanks very much mate for all your help.

Your right in what you say, in theory most things work out, but in practice it's ridiculous.

Cheers.
 

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