Cellar conversion...or 2 !!

[gazzaharwood]

Hi,
im in need of someones valuable knowledge again!!!

The story so far....

im converting an existing cellar and opening one up next to it!!!
There is a concrete floor in the existing cellar. in all the rooms above these cellars are original, sanded and varnished floorboards.....(which we intend to keep)
The second cellar had roughly 4ft by 12ft by 12ft of rubble and earth!!!!!
I have just finished removing this and found that the outside wall doesn't go all the way down like the internal walls...so i have left approx 2ft of the earth (actually consists of natural hardcore and stone) around this wall...

Here come the questions....

Im having a concrete floor laid in the new cellar...would i be right in thinking that this will consist of hardcore, sand, dpm and concrete??
i have been quoted around £600 for this! (10ft x10ft) and another (8ftx3ft)
once laid will i be able to lay underlay and carpet on top??
once the floor is layed i will be building a concrete wall to help retain the 2ft of earth left!!

in the existing cellar can i also place underlay and carpet on top of the existing concrete??

due to the floorboards above, my idea is to place hardboard in between the joists and then seal with silicone to stop draughts above and spillages below......then fill with loft insulation and cover with sound db plasterboard....can i still use downlighters with having loft insulation?? using downlighters due to height restrictions...

any ideas for some sound insulation??

any help will be greatly appreciated

many, many thanx!!!

Gazza!!!

 

[JerryM]

i think the lack of interest is that this probably should have been in building.

i have done a previous post "concrete floor for cellar questions" which would be worth a read (re Q1 concrete floor).

price sounds a little high for a quick fix. ask for mat/labour split then work out hourly rate based on time to do job and 2 people. depends what is being quoted if it's full spec (see Q1) then probably not far off. depends on the access.

Q3 once laid ok to lay underlay and carpet. would ideally not use the rubber underlay to help allow the concrete to dry out. you can get a sort of fibre/felt underlay which i use and is just as good.

Q4 in existing cellar would say no unless you put a dpm (vapour barrier) down first on top of the concrete to stop the damp.

Q5 on the floor boards just put insulation in and temp hold with chicken wire before fixing plasterboard. if you’re going to put spots in then you need to create a cavity around the spot with at least 2" clearance from the spot to any wood or insulation. ideally make sure you buy the fire rated "f" stamped spots (typ screwfix).

Q6 on sound insulation if you mean not music then i would say polystyrene which can be bought in big sheets and cut with carving knife. i think otherwise building regs would require rockwool which is expensive.

 

[gazzaharwood]

hi,
many thanx for excellent reply........just to clarify though as im a bit fick!!

Q1 why cant i lay underlay and carpet on existing concrete floor?? if i do have to use dpm can i still lay underlay and carpet on top of this (without fixing)
Q2 if i use polystyrene will it be safe??
Q3 will hardboard, loft insulation (100mm) and 15mm soundbloc plasterboard be enough to dampen noise down from exposed floorboards above?
Q4 do you mean firehoods for the downlighters? can i insulate upto them if they have these?? if they are just exposed would it be safe if i leave room around them?


ive since decided to do the floor myself!!!!!
£40 for 10/20mm hardcore (1 tonne)
£35 for roll of visqueen (300mu)
£200 for wet readymix concrete delivered!!!

many thanx again

Gazza!!!

 

[JerryM]

Q1 if the existing conc floor is not damp then underlay and carpet straight on top. suggest tape a square piece of clear plastic onto the concrete and leave 24hrs - if the plastic has water on the inside then you need to put some form of dpm before underlay otherwise the underlay and carpet will eventually rot. you could use the visqueen or an underlay used for laminate flooring which has a foam top but with dpm on underside (www.screwfix.com for example have them).

Q2 is polystyrene safe - i don't see why not as the polystyrene is effectively sandwiched between the floor board and the plasterboard. i suggested polystyrene as i've used it when putting in a full spec concrete floor. It's easy to use and good on price. to be 100% safe then rockwool is the answer. alternatively fit roofing foil over the polystyrene planks as you fit them. loft insulation i believe is not fire resistant either.

Q3 is 100mm insulation and 15mm plasterboard good enough to insulate the sound. i would say yes except for the hardboard. have slight concern that if the floorboards contact the hardboard (due to deflection) when walking on the floorboards then this could cause extra noise on the ground floor. ideally you need something soft to absorb the deflection in the floorboards as you walk over them. also note most loft insulation is not fire resistance either (only rockwool).

Q4 i don't know of fire hoods. what i know is that the "f" fire rated spots need 50 mm clearance around to any wood and i think 150mm above to any wood. what i was thinking of was creating a square cavity between the joists in the positions of the spot lights. this to create an air gap around the spot (2" clearance) and above it (6" clearance) where there is no insulation.

on doing the floor yourself sounds good. i have a mixer so i make the concrete myself (can easily barrow to where i want).

you will need to put some sand over the hardcore to stop it piercing the dpm (1" is std).

the easiest hardcore to work with is crusher run - i am not sure if the 10/20 hardcore is the same. the advantage of the crusher run is that it contains fine aggregate (sort of like grit sand) which helps to tamp the 10/20 aggregate down.

i presume you've got an easy route into the cellar from outside for the concrete. you may need a wheelbarrow to work your way out depending on the concrete route.

you will need a light/sturdy piece of timber (something like 150x25x 2m) to help level the concrete out and another heavier piece to tamp the concrete down (something like 150x50x 2m). if you can get someone to help then the leveller and tamper ideally need to be just short of the width of the room (particularly the leveller so you can zig zag as you pull the concrete level).

 

[gazzaharwood]

once again thanx for the very informative reply........and again i just need to get things clear in my head!!!!
Slightly confused over the polystyrene.....where exactly does this need to go? you said between floorboards and plasterboard...did you mean between the flooring joist and plasterboard.... plan to have floorboard, hardboard, insulation then plasterboard
can i still use loft insulation as long as i dont put near downlighters?

could i have....floorboard, hardboard, polystyrene, loft insulation then covered with plasterboard?

sorry for being so thick!!!

regards the concrete floor.....the visqueen roll i ordered arrived this morning so will se if the existing floor is damp. it looks as if its never been damp.......if it does need the visqueen can i just put underlay straight on top?

many thanx
Ficko!!!

 

[JerryM]

Gazza, i found you’re prompt on the fire safety of the polystyrene interesting as i think i recall polystyrene ceiling tiles are no longer permitted. i think you should contact your local building control office to get further advice. i know and have used rockwool in stud walls and it is approved by BCO.

for interest i carried out a fire test on loft insulation and polystyrene this morning (Unfortunately didn't have any rockwool to hand). The conclusion was that both are not fire resistant. i was happier with the polystyrene as it tended to absorb heat due to it melting whereas the loft insulation tended to smoulder. the foil made a significant difference. i am not sure on the how friendly the fumes would be from both. if the floorboards are in good order ie no gaps or you are covering with laminate or carpet then i feel the polystyrene would be fine if not then rockwool is the safest.

Test 1 - lit match laid on both. result polystyrene melted, loft insulation smouldered, match burned fully on both. flame on polystyrene extinguished faster than loft insulation

Test 2 - lit match laid on top of sawdust laid on both. result as test 1 but sawdust seemed to holdback the flame on both but smouldered more.

Test 3 - blowtorch on both. result polystyrene melted away but stopped burning as soon as flame removed. loft insulation burnt slowly but smouldered long after flame removed

Test 4 - wrapped kitchen foil around both and laid match. result flame extinguished before match fully burned on both. no real difference between them.

Test 5 - wrapped kitchen foil around both and blowtorched. result foil split open quicker on the loft insulation (typ 30 secs) than the polystyrene (typ 1 min)

 

[JohnD]

what product do you mean when you say "loft insulation?"

 

[gazzaharwood]

WOW, cant believe someone would go to these great lengths just to help a thicko!!!!!

I was intending to use the kind you get in a roll from wickes or sommat!!!

As a result of these tests ......
if i use kitchen foil to wrap whatever insulation i use in ....will it still keep its insulating and sound insulating properties??

Can i assume that Rockwool is completely fire resistant and would be safe to use with downlighters??

Could i just make a firehood out of plasterboard lined with kitchen foil and place this over the downlighter?

great thanx

Gazza!!!

 

[JerryM]

the loft insulation i've used is the itchy stuff i think the term is mineral wool (bought from B and Q but would shop around). the rockwool is quite different and so is the price (it's not itchy)

the only smoker in the family arrived this afternoon and instead of sending her outside as normal i asked her to join the test. we dropped a cigarette on blocks of both polystyrene and loft insulation both wrapped in kitchen foil. would not burn at all on either. she then used her lighter and that wouldn't get the foil to burn either.

i think it's crucial to use the foil if not going for the rockwool from the fire safety point of view. the foil will not affect the sound and insulating properties.

i think it's important not to leave a gap between the underside of the floorboard and the insulation (loud speaker principle that cavities increase the sound).

i don't think anything in building work is completely fire resistant and the electrician i know has integral spots as his No 1 fire risk. keep as much air gap as you can. the plasterboard idea is good around the spot but above needs to be left clear for the heat to escape. i've had a quick look in the screwfix catalogue which lists LV fire rated spots - this may be a better solution to the F rated LV spots but you would need to post in another forum and or contact a manufacturer for advice. i've only used the f rated type which need the air gap.

 

[JohnD]

you say that loft insulation (mineral wool or fibreglass) burned?

 

[JerryM]

yes i considered that the insulation burned. not in the way paper does ie with a flame. it remained hot with glowing embers after the heat had been removed. the material burnt much slower than the polystyrene which literally disappeared. what concerned me about the insulation was that it continued to smoulder for a long time ie was almost able to support its own burning where as the polystyrene burnt itself out once the heat was removed (because it was evaporating).

i pulled out the spec sheet for the spots i use, they are by Eterna LV Recessed Eyeballs 12v 20w MR16 Halogen lamp. these are "f" fire rated but have no hood. the required cavity space above the light fitting is 130mm and 50mm around. In screwfix i noted some what i think you are referring to as hooded spots which have a casing and "integrated intumescent material" (I know intumescent is a fire stopper material). i think these would be best if you don't want to leave a cavity in the insulation. i've not used them though.

Nb the Eterna spec sht gives the following Building Regulations link www.odpm.gov.uk then select Building regs from the popular links drop down box. i've had a quick look and it seems that you then need to follow the link to www.planningportal.gov.uk which has downloads of the regs. Looking a bit heavy though.

 

[gazzaharwood]

thanx again jerrym....
think im gonna go for fire rated downlighters with the rockwool insulation....
will i still need to leave a gap above the downlighter.....where will the heat go.....as above it there will be a 2"gap than hardboard then the floorboard...and around it there will be the rockwool insulation??

Is rockwool a material? as i notice this is a brand!!!

cheers
Gazza!!!

 

[JerryM]

i think the rockwool is a good choice. the itchy stuff would be a nightmare working it above your head (it's grim putting it down into a loft). i would try a few builders merchants along with the DIY's to get the best price.

even with the hooded fire rated downlighters i would leave a gap above. 2" sounds fine. You will get a spec sheet with the spots and you need to confirm that the 2" gap is ok.

i didn't realise rockwool is a brand. i think it's what JohnD is referring to as mineral wool. you can tell the difference visually it's in sheet form as opposed to a roll, keeps it's shape and it's not itchy. just ask for rockwool or equivalent at the merchants (i just ask for rockwool). use an old carving knife to cut it.

best wishes

 

[gazzaharwood]

hi once again...

can you not get the rockwool (mineral wool) in rolls??
when you say leave a 2" gap above the downlighter, does that mean the full length of the joist or just above the downlighter....sorry to be a pain, but ive only got one chance in getting everything right!!!
cheers
Gazza!!!

 

[JerryM]

understand no probs

as long as it's rockwool or equivalent then roll or slab (I have only found the itchy stuff in rolls and the rockwool stuff in slabs). i would call into your local builder’s merchants, see the stuff then shop round on price.

the 2" gap above the downlighter is just above the downlighter - not the full length of the joist. Don’t forget the 2” gap around the downlighter also. If you picture an inverted can then the gap inside the can and the downlighter should be 2” at the sides and at the top.