Jacob
What goes around comes around.
What's the best insulation to put under a concrete floor slab carrying a lot of weight i.e. a large wood burner boiler and a thermal store (1 and 1/2 tonnes)?
underfloor insulation
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Grahamshed
Established Member
I think the norm is polystyrene slabs on the basis that they do not really compress when weight is put on them. I have it between bearers under my chipboard flooring and that is holding machines I wouldn't have trusted just on chipboard.
Jacob
What goes around comes around.
Checked with supplier and they say same as Graham. 3 tonnes on a 3x3m slab is not much at all.
It's an existing suspended timber floor over rubble with 300mm from FFL to the hardcore. The slab will replace part of this. I thought 150mm concrete with reenforcement, on top of 150mm insulation on dpm, with insulation around the edges. A lot of insulation but saves on concrete and labour.
It's an existing suspended timber floor over rubble with 300mm from FFL to the hardcore. The slab will replace part of this. I thought 150mm concrete with reenforcement, on top of 150mm insulation on dpm, with insulation around the edges. A lot of insulation but saves on concrete and labour.
Yes as it's a section then ensure the slab is locked into place and can't creep over time, had a couple of jobs where builders had put in a base for an aga and after a year or two it's coming away from the wall!
Dean
Dean
Grahamshed
Established Member
ye Gods, that'll be a first :roll: =D> =D>Jacob":1yq857tr said:
Jacob
What goes around comes around.
Thanks for that - will bear it in mind. Maybe key the corners down to the hardcore by leaving out a bit of insulation.DMF":tcpi9c8n said:
MMUK
Established Member
100mm polystyrene will be plenty but I'd use a 200mm mesh reinforced concrete slab. Just make sure that the ground under the poly is as level as possible with no voids 
I would prepare the base, blind with soft sand about 1" thick, bed down and fit the DPM, lapping it up the sides and folding it into the corners. Then I'd lay the poly sheets and reinforcing mesh. Use a few Class B engineering bricks to act as legs for the mesh and then concrete away
I would prepare the base, blind with soft sand about 1" thick, bed down and fit the DPM, lapping it up the sides and folding it into the corners. Then I'd lay the poly sheets and reinforcing mesh. Use a few Class B engineering bricks to act as legs for the mesh and then concrete away
Jacob":1yzc2w4d said:
Yes could work, lots of ways of doing it to be honest but I'm not there to see! I would want a loose edge cast below ground or thickened up in places not against some loose hard core / rubble, or could stick a couple of pins in if it's loose on a complete side? May be easier if there is much in the way? Sides completely against brick work of course unable to shift.
MMUK makes a valid point regarding puncturing DPM as well, don't want to say the obvious but it's a consideration so if its smooth rubble, quite level with minimal voids the yes a layer of sand will do but if it's lumpy sharp stuff with voids then type 1 it first then sand.
Dean.
kostello
Established Member
Jacob":4ho9pr89 said:
I think extruded polystyrene has the best load bearing capacity
blackrodd
Established Member
As you say, 2 Cubic mtrs concrete will cover a 3m x 3m slab at 8" and weigh around the 3 ton mark.
Assuming i am not teaching you about sucking eggs etc. The average domestic garage floor should be around 6" but the 8" floor you intend, would not come amiss for some weighty items of machinery, only covering a small floor area.
If you don't want to mess about with brick "biscuits" and steel mesh, It may pay you to contact you're concrete supplier and cost out the price of concrete that has strands and polymers in the mix, taking the place of steel re-inforcing and making a straight forward job.
Don't forget the driver will encourage you to use loads of water,so he can get off quicker to the depot.
This is not a good idea as all the cement tends to go down under the sand, which rises up with the excess water, and that will be a really sandy and dusty floor that you can sweep every day and it's still always dusty, although a good dose of unibond will seal it .
Should you not have enough "hands" it may be a good idea to use a pump truck.
HTH Regarda Rodders
Assuming i am not teaching you about sucking eggs etc. The average domestic garage floor should be around 6" but the 8" floor you intend, would not come amiss for some weighty items of machinery, only covering a small floor area.
If you don't want to mess about with brick "biscuits" and steel mesh, It may pay you to contact you're concrete supplier and cost out the price of concrete that has strands and polymers in the mix, taking the place of steel re-inforcing and making a straight forward job.
Don't forget the driver will encourage you to use loads of water,so he can get off quicker to the depot.
This is not a good idea as all the cement tends to go down under the sand, which rises up with the excess water, and that will be a really sandy and dusty floor that you can sweep every day and it's still always dusty, although a good dose of unibond will seal it .
Should you not have enough "hands" it may be a good idea to use a pump truck.
HTH Regarda Rodders
