Foundation Problems Help needed quickly PLEASE

oldhead

Hello to all, I have just put in a strip foundation, the standard 4" Block + 100mmm cavity + (60mm insulation not in yet) + 4" block. The floor is also poured. I have a problem if i want to change my insulation to the recommended 2010 regs. I need a 140mm cavity. Is it safe to increase the cavity size by 40mm, by overlapping the blocks on the inner and outer leaf by 20mm. The reason i am asking is the i would like to allow for the new regs which are as follows:
1. 4" block + 40mm air cavity + 75mm insulation + 4" block + 38mm slab board.

2. 4" block + 40mm air cavity + 75mm insulation + 6" Quinn Therm Blocks.

3. 4" block + 40mm air cavity + 100mm Insulation + 4" block.

I would like to have option 3 with the 100mm insulation as you will have the solid walls on the inside. I don't like the idea of the plasterboards, plus the quinn therm blocks are quite expensive, plus i don't know anything about these type of blocks.

Can anyone help me out with this problem or offer me some advice, all ideas welcome. Blocklayer is coming back in about a 10 days.

Many thanks for taking the time to read the problem.

sinnerboy

stop now . buy the homebond manual. employ a professional . i believe this is the 2nd time you got this advice

sydthebeat

sinnerboy wrote: »

stop now . buy the homebond manual. employ a professional . i believe this is the 2nd time you got this advice

seconded.

muffler

Thirded

Builderfromhell

If your foundation is wide enough then you might be able to put an additional line of block all around the house. You then end up with 4"block+ 4" block+cavity+4" block. Above the floor you would then increase the cavity size. For example 4" block + 140mm + 4" block.

alternatively, take away the external row of blocks from foundation to Floor level and re-lay with wider cavity.

all above dependent on adequate foundations.

as stated above, professional advice required.

Quazzie

Increasing the cavity will inevitably increase either the overall outside dimensions or decrease the internal floor area. In terms of planning permission are you allowed to change outside dimensions even by this marginal amount.

muffler

Quazzie2002 wrote: »

Increasing the cavity will inevitably increase either the overall outside dimensions or decrease the internal floor area. In terms of planning permission are you allowed to change outside dimensions even by this marginal amount.

Did you ever find a block layer that wouldnt be off by that amount

Quazzie

I had a feeling someone was gonna say that. My question was more theoretical than anything else. How far off planning dimensions is generally acceptable??

muffler

Strictly speaking you cant deviate from the originally approved size.

Now if I were to answer your question truthfully I would have to ban myself from the forum as the charter states there is to be no discussion on flaunting the planning regs.

sinnerboy

Quazzie2002 wrote: »

Increasing the cavity will inevitably increase either the overall outside dimensions or decrease the internal floor area. In terms of planning permission are you allowed to change outside dimensions even by this marginal amount.

This would be a matter for the certitying Architect . ..... if one was appointed ( OP - please note )

Quazzie

Thanks Muffler. As fun as it would be to see you give yourself a warning I'll accept your answer. Now I think I might have taken this thread on enough of tangent back OT now.

oldhead

how is a homebond manual going to answer my question, i am asking here in the hope there is a professional that can give me some advice.

muffler

oldhead wrote: »

how is a homebond manual going to answer my question, i am asking here in the hope there is a professional that can give me some advice.

1. Homebond manual will give you a lot of info coupled with photos.
2. You should be asking your architect/engineer about this.
3. Its in the charter that we cant give advice regarding structural elements.
4 You didnt even bother to say what width your foundation was.

sinnerboy

oldhead wrote: »

i am asking here in the hope there is a professional that can give me some advice.

You have been given advice - from several professionals. You seem reluctant to take it .

Don't listen to those who say "it's not rocket science" . Building a house to meet current building regulations is not easy .

You aren't out of the ground and you are in trouble already .

Do yourself a BIG favour . Stop now and employ a professional. You can't do this on the internet

smashey

oldhead wrote: »

how is a homebond manual going to answer my question, i am asking here in the hope there is a professional that can give me some advice.

I'll tell you why you're asking this here.

As sinnerboy alluded to, you're in trouble. So, rather than speak to your architect/engineer, you came on here seeking free advice. The advice given so far has been good based on the fact that nobody on here has seen your site.

Speak to your architect/engineer. After all, they are going to have to sign off on your house and it will be their PI at stake.

Locked.