Construction details Solid timber ground floor

Jollyman

Guys was wondering could any of ye point me in the direction of a website that will show me the detail of construction for a concrete subfloor with 9x2 joists and eventually solid flooring on top. I know the joist hangers are no longer in use.

Mellor

Homebond should have details.
Quick question, why the concrete subfloor if there is going to be full sized joists also

Jollyman

Thats what im wondering, i unfortuately dont have a copy of homebond, have been looking at the kingspan insulation site for a detail. Do i need to fill my base with hardcore put in a radon barrier 100-150 mm of concrete; joists insulation between joists plywood on top of this and fix the flooring at another stage.

What is the normal detail with this?

dingdong1234567

I would put the insulation under the concrete floor.

What you can use instead of the joist hangers is ordinary brick/engineering brick and the put your joists on that. The brick will be in rows at designated centres as not to allow deflection in the floor joists.

The brick is built in a honeycomb formation to allow air to pass through. On top of the first row of brick you would lay your DPC to prevert moisture rising to the floor elements.

If your puttin in a timber floor like this, its wroth while installing some air vents from the outside walls to circulate air under the floor to keep damp and moisture to a minimum.

muffler

Do you by any chance have a raised floor level - ie. maybe a metre above ground level? Sounds like you are going to use a suspended wooden floor which would be a different thing.

Do your plans not show a detailing for this or has your architect/engineer not supplied you with this detailing?

Jollyman

Thanks dingdong, seems like a good alternative just on the insulation would it be less effective when there is such a gap between the floorboards and the concrete 9" for the timber and maybe three four rows of brick ptential of 20inches or so?

dingdong1234567

Jollyman wrote: »

Thanks dingdong, seems like a good alternative just on the insulation would it be less effective when there is such a gap between the floorboards and the concrete 9" for the timber and maybe three four rows of brick ptential of 20inches or so?

What you want to achieve is a 'thermal barrier' between the elements of the building i.e the concrete floor and the hardcore. The insulation below the concrete floor will prevent the heat being conducted through to the hardcore and help the concrete floor retain some heat.

The heat loss in the void under the floor would be minimal IMO.

This is my understanding of how it should be, put for your own piece of mind you should consult the 'blue book' as i call it.....Homebond. It will have every builders detail you need.

Jollyman

If only i could get my hands on the blue book! New version is not out until april!

Yes it is above ground level, and i suppose you would call it a suspended wooden floor, but as dingdong said for the strength of the floor the bricks would be a good idea.

Ill take some pics closer to the time and stick them on the blog.

Mellor

That is a bit clearer, was a bit early and I took you up as having joists "on" the floor. By the way, in the new edition of homebond, this detail is unlikely to change.
Tassel walls are probably easiest, what is the deepest fill you have?
There has to be 150mm min between joists and sub-floor, and tassel walls are 75mm min. Centres from IS444

I would put the insulation under the concrete floor.

.............

If your puttin in a timber floor like this, its wroth while installing some air vents from the outside walls to circulate air under the floor to keep damp and moisture to a minimum.

Its more than worth hile having vents, its a requirement. There is a min requirement based, its 1500mm2 per metre.

BUT having the insulation under the concrete is not great imo. The space between the joists and slab is warm side, and alot of heat will be lost through the air vents, not through the air gap but physically passing out to the outside.

dingdong1234567

Jollyman wrote: »

Guys was wondering could any of ye point me in the direction of a website that will show me the detail of construction for a concrete subfloor with 9x2 joists and eventually solid flooring on top. I know the joist hangers are no longer in use.

Anyway jollyman, i hope this helps with your query. After all that is what this thread is about?:D