Foundation height issue

[Footsoldier888]

Thanks - interesting. Not having any practical experience here, I would be worried too!

It would seem you have a conflict. I am not clear how this situation has arisn since you have detailed drawings.

Or can the telescopic air vents be incorporated into the foundation???

 

[^woody^]

I am not clear how this situation has arisn since you have detailed drawings

Au contraire. The situation has arisen purely because he does not have detailed drawings.

Already a grand down, and may be adding to that.

 

[Footsoldier888]

I see. Well sort of.

Where has the fault arisn? Is it not having all the details on one plan or is it a lack of detail altogether?

 

[iwanttodiy]

It would seem you have a conflict. I am not clear how this situation has arisn since you have detailed drawings.

Or can the telescopic air vents be incorporated into the foundation???

Sorry, I don’t understand. I don’t believe I have a problem with the air vents? They will be cut into the 2nd course of bricks above the retaining wall. And below the cavity tray. The other end of it will be cut into the Block below the inner leaf DPC and above the foundations. I haven’t drawn the waterproofing detail into my drawing yet. And yes, I will need to appropriately seal the tanking layer.

I see. Well sort of.

Where has the fault arisn? Is it not having all the details on one plan or is it a lack of detail altogether?

The problem is, although I have drawn up the details for the builder to follow such that I would end up with a 40-50mm void, he plans to only give me a 20-30mm void.

By the time the timber joists (45x170mm) go in I don’t have the minimum void under the joists to meet building regs.

Hopefully I can convince him to pour only 800mm of concrete instead of 1m of concrete

 

[Notch7]

Most builders Ive worked with set the foundation concrete level themselved. Also same with reduced dig for oversite.

Builders usually want to know finished floor heights, floor make etc, then work down from that.

A builder would dig out the foundation trench, then if the house is brickwork would pour concrete to finish a bit below a mortar joint. The idea is to be able to have a thickish joint to start to take up any outnof level, then lay blocks and bricks as required, keeping to gauge to get up to dpc level.

With timber or concrete beam suspended floor the builder will again work out the total floor thickness to see at what level he needs to leave enough ckearance below the joists / beams.

Its all pretty standard stuff. Every builder would know how to do it.

Get you builder to mark a datum, say dpc or underside of doors, then mark out the make up the job requires.

You dont need 150mm clearance from underside of joist to top of foundation, but you need to fit in your telescopic vents.

You do need 150mm clearance between underside of joist and soil or blinding - if you are blinding with concrete or other material.

 

[^woody^]

What you need to do is ask the builder to kneel in the trench with a tape, and then quickly pour all the concrete in. Because that would be the best place for him.

But this does sound like its going to be an entertaining build.

 

[iwanttodiy]

What you need to do is ask the builder to kneel in the trench with a tape, and then quickly pour all the concrete in. Because that would be the best place for him.

But this does sound like its going to be an entertaining build.

Funny you mention that. We actually found some bones whilst excavating the trench....

On a serious note, we’re not going to the top! And hopefully I have enough void.

You dont need 150mm clearance from underside of joist to top of foundation, but you need to fit in your telescopic vents.

My party wall side of the foundations are designed to be eccentric. It will protrude about 300mm from the inner leaf wall. A joist is pretty much going to be running the whole length of that above the foundation, hence my worry. Also the top of the pad foundations will be the same height as the rest of the foundations thus, a joist will be running above that. Based on my understanding, the bottom of the joist to the top of the concrete will still count towards a minimum 150mm ventilation requirements?

Otherwise, excavating the earth between the foundations is not a problem.

Air brick wise, if I don’t have space, I can just have it coming out on the same level as the joists. Which is pretty much what my existing house did.

 

[pilsbury]

But this does sound like its going to be an entertaining build.

As mine is nearing the end, you need another jolly. In a couple of months when I’m done I’ll post a project thread. Your sides will hurt for weeks.

 

[iwanttodiy]

As mine is nearing the end, you need another jolly. In a couple of months when I’m done I’ll post a project thread. Your sides will hurt for weeks.

Are you doing it all yourself or you contracting bits?

 

[pilsbury]

Are you doing it all yourself or you contracting bits?

Myself. Funds are super tight..... as am I. Also I thought this building game would be easy. Come to the conclusion it’s not.

 

[iwanttodiy]

I’ve got someone to do the works, still stressful and not easy...

 

[Notch7]

I’ve got someone to do the works, still stressful and not easy...

Did you get your concrete poured today?

Is the builder now buried in the trench?

 

[iwanttodiy]

Yes it got poured. It’s just about at the right height. Unfortunately adding the Builder would have raised the level of the concrete too much