Finishing an attic space

[Marticus100]

Hi all,

I'm in the proccess of finishing a new home, and whilst our contractor is finishing all the living spaces we also have a small attic space i would like to use for storage and such.

Currently the attic is just open beams with insulation layed between them.

Is it just a simple case of now laying mdf over the beams to cover the insulation, or do i need to account for ventilation etc?

 

[SimonH2]

Nothing like putting the cart before the horse

Ideally you should have thought about this before you got to the finishing stage.

The ideal would have been to put down larger joists (or fabricated trusses). I assume you now have 3 or 4" joists with glass fibre insulation between and over - that's now going to be a right PITA while you finish the loft.

If you just board over then a) you have "not a lot of support" and b) you'll only have 3 or 4" of glass fibre insulation which is only 1/3 of current recommendations.

In SO's house i'm part way through putting 4" Kingspan (or similar, unbranded seconds from Seconds & Co) between the original joists, cross joisting with 4x2 CLS and 4" glass fibre between the cross joists. By my reckoning that's roughly equivalent to 12" glass fibre.

 

[tony1851]

do i need to account for ventilation etc?

No, not if you're putting the boarding directly over the ceiling joists and insulation.

 

[Marticus100]

Nothing like putting the cart before the horse

Ideally you should have thought about this before you got to the finishing stage.

The ideal would have been to put down larger joists (or fabricated trusses). I assume you now have 3 or 4" joists with glass fibre insulation between and over - that's now going to be a right PITA while you finish the loft.

If you just board over then a) you have "not a lot of support" and b) you'll only have 3 or 4" of glass fibre insulation which is only 1/3 of current recommendations.

In SO's house i'm part way through putting 4" Kingspan (or similar, unbranded seconds from Seconds & Co) between the original joists, cross joisting with 4x2 CLS and 4" glass fibre between the cross joists. By my reckoning that's roughly equivalent to 12" glass fibre.

sorry not sure if i have explained myself fully.

the house was bought developed to a certain point, my contractor is making ajustments to the first fit, and then completing the second fit.

We haven't asked him to look at the loftspace because in theory it's fine as it is, and it would only be used for storage if at all.

currently the loft is insulated between the beams and the rafters, it hasn't been boarded however.

all i want to know is if i can throw some board down on the floors and possible some on the sides over the rafters.

or will i need to leave gaps between the boards for ventilation for example..

do i need to account for ventilation etc?

No, not if you're putting the boarding directly over the ceiling joists and insulation.

thanks

 

[SimonH2]

How deep are the joists ?
If they are only 3-4" as is common for supporting nothing but a ceiling then you'll have poor insulation if you just board over them. My guess is that you'd not meet the energy efficiency parts of the BR. Rigid foam (aka Kingspan etc) is roughly twice the insulation value of glass fibre - so 5-6" would be roughly equivalent to the 10-12" recommendation for glass fibre.

 

[geraldthehamster]

Is it just a simple case of now laying mdf over the beams

Chipboard or plywood. Not MDF.

Cheers
Richard

 

[Marticus100]

How deep are the joists ?
If they are only 3-4" as is common for supporting nothing but a ceiling then you'll have poor insulation if you just board over them. My guess is that you'd not meet the energy efficiency parts of the BR. Rigid foam (aka Kingspan etc) is roughly twice the insulation value of glass fibre - so 5-6" would be roughly equivalent to the 10-12" recommendation for glass fibre.

Thanks for the info, i'll need to look into it further, as it is i've only stuck my head up there a few times, so will need to have a proper investigation.

Is it just a simple case of now laying mdf over the beams

Chipboard or plywood. Not MDF.

Cheers
Richard

lol of course, long day.