Building a base for a full height edwardian conservatory

[hunting]

Hi Guys`s,

I am in the proccess of putting up a new full height Conservatory outside our kitchen, going for the triditional concerete base, which
needs to be 4 inches hight to level with the kitchen floor, i would like to put a course of 2 bricks on the outside edge to give me a nice finish, any ideas as to where the damp course needs to be please? And do i need any footings as such for it? The unit is 3 metres by 2.4 metres the edwardian type!

Thanks

 

[Alastairreid]

Yes you will need footings, the dpc needs to be a minimum of 150mm from finished ground level.
You need to dig enough out for your slab to accomodate hardcore, 100mm concrete, insulation, sand blinding, dpc.

 

[hunting]

Hi Alatairreid,

How deep do you think the footings need to be? Idealy i would like to keep the mess to minimum if i can, any suggestions?

By the way, what do you think of single row of bricks for the cil to rest on? Is it enough? Or should i go for a 9 inch wide brickwork?

Thanks

 

[freddiemercurystwin]

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• freddiemercurystwin
• 11 Oct 2011
• 1

 

[hunting]

Thank you for the image!

 

[^woody^]

i would like to keep the mess to minimum if i can, any suggestions?

You either get the mess at the start when you dig out and do it properly, or the mess afterwards when it starts sliding down the garden

 

[^woody^]

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• freddiemercurystwin
• 11 Oct 2011
• 1

What's the point of that internal leaf?

 

[freddiemercurystwin]

Supports the edge of the slab, in case the hardcore ever drops over time and tears the dpm as can happen, can't build a purely ground supported slab down this neck of the woods anymore for that reason, BC won't allow it. The OP can leave it out, I don't care.

 

[theoldun]

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• freddiemercurystwin
• 11 Oct 2011
• 1

What's the point of that internal leaf?

Surely the section gives you the answer.
oldun

 

[^woody^]

Untitled

• freddiemercurystwin
• 11 Oct 2011
• 1

What's the point of that internal leaf?

Surely the section gives you the answer.
oldun

No, and I was bored

OK pops, look at this one

You may notice that curiously enough, this floor slab is not resting on any wall. Why not? Its a typical method of construction

Could it be that it does not have to?

So is there a need to build an inner leaf?

So what if the slab is bearing on a wall and the fill drops? Well then you get a potential shear point, so where slabs are bearing there should be some reinforcement in the slab

 

[freddiemercurystwin]

Nobody is suggesting the slab is gonna break in half but if the hardcore has not been piled down very well and compresses slightly over time the edge of the slab can drop too, potentially tearing the dpm if its lapped into the wall. Come on ^woody^ ain't brain surgery.

 

[^woody^]

but if the hardcore has not been piled down very well and compresses slightly over time .

I don't think you can use that to justify it, because you just make sure that the fill is compacted.

It's just an opinion here, which I am going to throw out the the forum, but one should not design on the basis of fill compacting or not being done correctly. Otherwise were does it end ... what if the foundations compact, what if the mix is not right, what if, what if?

You just make sure it is built properly

So there is no need to bear the slab on the wall, but if there is (ie a suspended slab) or if there is likely to be a suspended slab, then it would make sense to design the slab to be suspended and include reinforcement

And from a longer term maintenance point of view, its easier to deal with a slab that has settled (or it may not need any work) than it is to deal with a cracked slab

Don't forget that the external walls and foundations will settle and move naturally over the seasons too, so that again increases the risk of cracking and is another reason to keep the slab independent. More so with extensions and additions

 

[freddiemercurystwin]

Aye but like it or not the hardcore can settle taking the slab with it and in a typical build it makes little/no difference to cast the slab onto the inner skin.

The industry is turning to full fill insulation in cavity's as we all know the potential pitfalls with partial fill insulation, same issue: standards of construction.