raising the floor level

[andcal]

I am in the process of extending kitchen into garage and was unsure of the best way to raise the floor level of garage up to suit kitchen.concrete slab in garage and in kitchen about 170mm difference. Had different ideas from a builder friend and 2 BCO's who have visited. Ideas include a floating floor built up in polystyrene and rigid insulation then chipboard then finish, also rigid insulation then 75mm screed then finish.The first BCO suggested a timber frame with insulation between joists. Well and truly confused anyone got a suggestion

 

[Chukka63]

i always use the celotex and floating floor method.170mm equates to 18mm chipboard,DPM,100mm celotex.you then have 52 mm to build up.as previously mentioned i personally would do it with jablite.cheaper than celotex.if there is a slope on the garage floor ,i just use sharp sand to level it from the highest point.should be the rear of the garage but you never know.hope this helps.using chipboard means you could do it yourself and you can work on it imediately and theres no drying out to occur.

 

[andcal]

thanks for the advice chukka, that did seem the easiest route to take from a diy point of view. The chipboard floats also or is that glued or fixed somehow? you said the DPM between chipboard and celotex would it not be below everything on top of concrete slab?

 

[Chukka63]

it use to be dpm on the concrete and then they changed it to above and glue all the joints of the chipboard but leave an expansion gap at perimieters.skirting will cover this gap later.

 

[moodygaz]

Would this still be a viable way to raise the floor if it needed raising by 260mm and you needed to put up stud walling to dryline the garage walls as the outside walls were only single leaf?

 

[Chukka63]

start your stud wall on the garage slab,lay some dpc under the sole plate,so it can be tucked up to lap with the DPM.then floor the room and then board ya stud walls

 

[moodygaz]

Would the insulation under the floor compress over time if you had a table or kitchen units etc on it?

 

[Chukka63]

this type of floor is used all the time and no it wont compress the insulation.unless you forget to put the chipboard down hehe

 

[Chri5]

Would the insulation under the floor compress over time if you had a table or kitchen units etc on it?

What makes you think it would ?

Am I not right in thinking that the celotex would still end up as fillers for some joist framing on the sub floor to allow support, strength and fixing of the floor surface ?

Or is the intention to just drop celotex on the floor and simply skin it with a floating chipboard floor.

 

[moodygaz]

If you use joists, then you have to suspend the floor on joist hangars and insulate between joists as the building regs say you need a gap of at least 150mm from slab to bottom of joists for ventilation (and airbricks fitted in walls to supply said air). Therefore you need 150mm plus depth of joist plus flooring thickness for the minimum difference in floor levels. If this cannot be achieved you can just fill the gap between the slab and floor level with rigid insulation boards, the chipboard flooring is then laid on top. Although the flooring is glued together it is not fixed to anything thats why its termed a floating floor. (hopefully I've got that right, if not I'm sure someone will put me on the right track!)

 

[punkyb]

Hi all, just refreshing an old topic here, with the celotex, then the DPM and WBP, would this provide a stable enough floor for tiling on? I was looking at using levelling compound then building a frame, but this seems like an altogether easier route