mimigoodspirit
Member
Hi,
Does anyone have any ideas on how to improve our floor r-rating - it is really cold to walk on in winter - but we can't fit under there to install insulation below. Should we add another layer of timber floor above ? We could fit another 30-50mm in.
sunbeam
Member
I certainly noticed quite a difference in winter/summer temps, after I put a floating floor in the living room. I went with the thickest foam underlay I could find for the floor panels. Cost a bit more but I figured it would be worth it if it helped insulate the floor. The original floorboards had small gaps and after taking up the carpets and going with polished boards around 15 years ago I put up with the cold for way too long. Fairly straightforward job to do and underlay has put a little 'give' in the floor which is nice. Half of the room was too close to the ground to get to as the house is set on sloping land
mimigoodspirit
Member
Benny, I'm not sure about that as I don't want to create a paradise for vermin & it would take a hell of a lot of filler material.
SK
Member
We're looking at underfloor insulation like you were for the same clearance (30 cm at back section and the rest 50 cm or so).
We had someone quote $6000 for a 4 bedroom house. They wsaid they would be able to do it with our restumping (also with the old ducts removed underfloor.
Would be interested to see what it is per sq metre.
I've been told by insulaters who refused to do it the underfloor doesn't matter because its only 10% loss/gain
arttt
Member
Benny said:
Is it sealed around the outside ? Would it be feasible to make small access holes and then pour in some loose fill like poly beads or what they pump in to wall cavities - shredded batts ?
Dont do this.
Subfoors are designed to have airflow (thats whey there are vents around the edges) as moisture comes up through the soil below the airflow dries it out.
Without that airflow you end up in mold and rot heaven.
peuckers
Member
We renovated our 11yr old weatherboard a couple of years ago and our builder had allowed to install insulation under our newly polished hallway. At the end of the job he said he "couldn't" insulate due to lack of access. We do have a lot of heating ducts and plumbing under there and probably 40-60cm for most of it. I'm wondering if spraying some expanding foam to the underside of the floor would help? I guess it would at least seal some of the gaps (in one spot I can feel drafts coming through!). We have rats in the area and past evidence of termite damage so I'm keen not to encourage vermin by doing a half-arsed job with batts 
I've put off crawling under there for nearly 2 years now - time to bite the bullet...
Johnnojack
Member
Yep rats and mice will move in to their warm new fibreglass batt home in a flash. Spray on foam could be the go especially in inaccessible spots. Foil covered foam boards cut carefully to exact sizes required for each spot would be best. Spray foam could still be used to fill any gaps.
Morbo
Member
I just stapled some brather fil underneath.The realative humidity in that enclosed space is more stable than outside and mostly its drier. Expol is messy lots of offcuts and you have to stick it into a yellow bin in Germany,at least they would recycle it. You will dind 2-4 degrees between outside and inside that insulated space. The temperature in the subfloor space is more balanced than outside anyway.
jdaley
Member
I have installed underfloor insulation in about 300mm space, but its not pleasant.
I stapled the insul foil , using an air operated stapler and it took 3 days to do about 150 sq metres. Parts of the floor were higher.
I use expel at my home and I found it greta, I measure the joist widths and choice the block which suits, I have also been able to use all the offcuts as well by stacking them on top of the sheets, I do have 200mm joists.
I'm halfway through doing this - old house with bugger all crawlspace 
For one smaller area I used Expol batts and aside from being a bit expensive and sometimes tricky to size correctly (as my joists aren't all the same width), they are pretty straight forward to install & no compared to batts.
I have 100mm joists so also adding a layer of Silverfloor (Ametalin product) under the joists as an extra layer & an air seal.
But for a larger area I purchased sheets of 10mm Foilboard - I'll cut these to fit the joist space and (as my cutting wont be perfect) will place a few nails below them to keep them secure. I'll then add Silverfloor as above. The Silverfloor works better with a bigger airgap so the 10mm Foilboard leaves plenty of space.
Crawling around is a crap job....but hopefully worth the extra comfort.
Doing it from the top is next to impossible, however with access from a cut out in my boards I have been able to slide Expol batts up a joist gap using a stick and maybe got the batts 2-3m along.....but you'd need a lot of cutouts for the whole house!
