Home  5  Books  5  Magazines  5  News  5  GreenPro  5  HelpDesk  5  Your Cart  5  Register  5  Green Living Forum
Not signed in (Sign In)

Categories



Green Building
"The most popular book on green building in the UK today."
New fourth edition in two volumes!

Order both books now for the combined price of just £17.00
and free delivery!

(free delivery applies to UK addresses only).

Or get both books for just £15.00 if purchased at the same time as a subscription to Green Building magazine





Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
 Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




Fundamentals: Partial fill, floor insulation?

Bottom of Page

1 to 8 of 8

  1.  
    • CommentAuthorstephendv
    • CommentTimeSep 14th 2010
     
    Suspended floor, ventilated below - it's actually a house on stilts. Joists 22cm deep. Subfloor made from 18mm OSB3, taped and glued to joists. The fastest way to install the insulation will be to screw and glue 9mm OSB onto the underside of the joists, then install 12cm rockwool onto this. But it would mean that there's a gap of 6cm between the insulation and the floor - is there any problem with this?
    •  
      CommentAuthorSteamyTea
    • CommentTimeSep 14th 2010
     
    Not really a problem, though why not fill to the floor?
  3.  
    Posted By: stephendvBut it would mean that there's a gap of 6cm between the insulation and the floor - is there any problem with this?
    Any air gap can lead to unwanted air movement & cold air bypassing the insulation. Better to fill the void if possible.

    If you're worried about the insulation getting in the way when you're trying to fix the OSB then you could staple insulation support netting to the underside of the joists & then fix the OSB over that.

    David
    • CommentAuthorevan
    • CommentTimeSep 14th 2010
     
    Um, 220mm joists with 120mm of rockwool? Doesn't that leave 100mm unfilled?

    I'd use two layers of the rockwool, compressed very slightly, right up to the underside of the floorboard.

    If you've got that much space and access, blowing warmcell in from the ends after boarding it might be quicker and easier, if time is more valuable than money :)
  5.  
    For the same money as OSB you could fix 100mm EPS sheets to the underside of the joists, it would be more breathable and it would stop condensation forming on the bottoms of the joists. You could then even consider blocking off the vents which would improve your airtightness as well!
    • CommentAuthorstephendv
    • CommentTimeSep 14th 2010
     
    Thanks all, yes it's 10cm of space. The rockwool arrived yesterday, and I have the itches to prove it. Since we'll likely have quite a lot of air movement underneath the house, I take your points about air potentially blowing into the rockwool. I asked for a quote for blown cellulose a few months ago and discounted it as an option because of the astronomical price.... but since the floor isn't done yet I can install myself without a blower, and it turns out that it's only slightly more expensive than rockwool for the material alone, so I'll fill the rest up with cellulose. Sorted.
    • CommentAuthorevan
    • CommentTimeSep 14th 2010
     
    Hmm, again if it was me I would probably just use two layers of rockwool - mixing insulation types isn't supposed to be a good idea, and filling warmcell by hand is a complete nuisance! I'd also be concerned about it getting damp if the rest of the house isn't on top yet...
    • CommentAuthorstephendv
    • CommentTimeSep 14th 2010
     
    Viking house, unfortunately I already have the OSB in place so am stuck with it. The rockwool I have is 60cm, but my joists are 40 - (It's what the local supplier had in stock), so I'm going to have to cut all 50m2 of it. Would you still say warmcell is a nuisance? What's the best way to do it by hand? Home made rotor attached to a drill?

1 to 8 of 8

  1.  
Add your comments

    Username Password
  • Format comments as
 
Back to Discussions Top of Page
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press