Best loft insulation - 2 bed house

DJMK4

DJMK4

DJMK4

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1 Dec 2004
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S.Wales
Hi all, planning at some stage to sort the loft out. There is loft insulation up there but it could do with replacing with something better. Could.be the origonal insulation when house was built . I was going to buy some and do a section at a time clearing out old and cleaning up anything lying about. Make the spotlight wirings are tidy and then lay fresh new insulation down which do a good job..

What's the best cheapest stuff? I heard summer is a.good time.to buy ?



I find my place gets cold quickly . I'm.having carpet and underlay sorted soon which should also help

Is it better to lay the insulation down then put boards over with legs or without legs? I have led.downlights so need to make room for.them.and where they are need access..
 
You shouldn't crush insulation and you should aim for 100mm minimum.

If you intend to board over it then you should use legs or other raised solutions. Loftzone.co.uk have a pretty neat solution.

Don't use timber cross members or similar off the joists as you might encourage cold bridging.

You'll need to check the fire ratings / application of your LED down lighters to determine if they need fire hoods, clearance etc.
 
Yeh the led downlights were upgraded by myself..there was lap ip20 ones in when I bought but swapped them for brushed metal JCC IP20 fire rated.. they need just little bit of clearance but they are cool running and have plenty of ventilation

I think for now a refresh of the insulation would.be good as it's old and messy currently . Was after a ball park.figure doesn't have to be accurate

I have a few temp boards up there but can board some areas later down the line
 
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Interesting I didn't know.they had those .I thought you had to leave them uncovered . iP20s come with the fire rated metal casing around them. I didn't think.you.were then supposed to cover that with something..

At the moment there are just holes cut in the insulation around where the light installs are going in to the ceiling board

Cheers will check those out or other similar products
 
One of the main reason to seal round them is to stop hest loss around he light fitting. Its amazing how much heat will escape even around small downlighters.
 
put fire hoods over the spots and put 2 layers of 200mm knauf roll down (400mm total)

often on multi but offer if you scour the net
 
270mm rock wool or equivalent is the recommended.

I have 200mm rockwool with boards on top which is probably near that. The boards stops air movement and heat loss.

Reminds me I need to seal the airgap around my new loft hatch. Only 1-2mm but it all counts
 
My bathroom vent has an insulated exhaust vent and the actual fan has its own built in flaps to stop cold air coming backnthrough the vent
 
Psycho Sonny said:
What do you guys do with things like air vents in bathrooms?

If you care so much about 1mm gaps what about the huge 10cm vent for allowing steam to vent outside?
Click to expand...

That’s on the wall not a ceiling, heat rises. And it’s a 130x70cm hatch...

Plus I have a closing bathroom vent
 
Cool cheers for reccomendations all. Will get those fire hoods if they are vented..as said my downlights are already fire rated. But yeh this will help them actual.metal casing and wiring being disturbed.a bit more and help with warmth escaping .

These are the current IP20s I have in the master and spare room

uSjwMLx.jpg


These are the IP65s I have in the bathroom.

2dUDBTS.jpg


Apologies about the cut out hole in second pic I am smoothing around it at present.

Thanks for advice all I'll go to some of the mentioned rockwool at a decent mm
 
Insulation can sometimes be cheaper in the summer, but I don't recommend fitting it in the summer as it's not a pleasant experience! I just used Knauf 200mm (over the top of the existing layer) stuff as that what my local shops sold. I was skeptical about the plastic loft legs, but they are actually really good. Fit them while you are doing the insulation as it's easier to see where the joists are before you stick tons of insulation down.

Dave
 
Remove the old insulation.

Call one of the energy suppliers, let them come around and do a site visit. They will fit everything for free.

(while it is empty its a good time to screw in the loft legs etc to board it all out after they have gone.
 
The celotex style rigid sheet insulation generally have the best r values going plus thermal conductivity 0.022 W/mK compared to 0.044W/mk for loft rolls but are not generally used for loft insulation as they are a pain to cut and shape compared to unreeling a roll of loft insulation. If you are doing a loft conversion though its.what you need as it is designed for wall and floor insulation
 
recommend levels are 300mm of high quality loft roll

remember not all insulation is created equally - I used kanuf earthwool which is 50% better than most at 0.032W/mK

I did 200mm inbetween the rafters then another 200mm on top laid perpendicular which give a U-value of 0.1

in the converted parts of the loft I used 125mm of celotex which gives a u-value of 0.18 (lower is better) and costs a lot more
 
eviled said:
recommend levels are 300mm of high quality loft roll

remember not all insulation is created equally - I used kanuf earthwool which is 50% better than most at 0.032W/mK

I did 200mm inbetween the rafters then another 200mm on top laid perpendicular which give a U-value of 0.1

in the converted parts of the loft I used 125mm of celotex which gives a u-value of 0.18 (lower is better) and costs a lot more
Click to expand...

All the Knauf rolls I see are 0.044W/mK:
https://www.travisperkins.co.uk/Kna...Insulation-Roll-44/p/9000200436#tab-techspecs
https://www.wickes.co.uk/Knauf-100mm-Space-Loft-Roll-Bottom-Layer-Roll---8-3m2/p/166877
 
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