Chipbord floor advice

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RickW

252 posts

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# 138352 31-Dec-2013 12:00

Hey guys,

We have just taken back possession of our rental property and I'm in the process of gutting it after having some terrible tenants.

The house has always smelt damp and we are trying to remedy this by installing polythene under the house and removing all the gib on the external walls and packing them out by another 45mm but staggering the studs to create as little thermal contact as possible and installing closed cell spray foam insulation plus thermally broken aluminium windows. (We installed pink batts about 3 years ago in the ceiling to r6)

What I'm trying to weigh up is the OSB floor in a couple of the rooms smells extremely musty in two of the rooms is it worth trying to paint it with a oil based paint to seal the smell in or just rip the floor up in those two rooms and lay new osb?

timmmay

15332 posts

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# 959562 31-Dec-2013 13:03

Research spray wall insulation carefully, I've heard stories of dampness. I've had it, and it's fine.

Putting polythene under the floor and under floor insulation made a HUGE improvement to the dampness in my house. Do it properly, stake down the polythene so it can't move, tape it to piles, etc. I'm not sure if it's the polythene or insulation that helped most, probably the polythene, the insulation didn't make much of a difference to warmth. New carpet with a thick underlay did as much.

Carpet could be musty too.

mattwnz

15210 posts

Uber Geek

# 959572 31-Dec-2013 13:33

For what you are doing, you will very likely need building consent. Spray insulation s also not common in nz, and from what I have read, it can shrink and create gaps, and am not sure how it is if it comes into contact with wires and pipes over the long term. . A wool type is possibly best, as it breathes, especially if you have moisture. I am not sure if the expense stagging wall studs is worth it, as a lkot of work and additional expense, and the council will probably want drawings and specs. Possibly better inside to have 140 thick framing and tick insulation. . Most heat is lost throught roof and windows anyway.
If you have old particle board flooring, and it is damp, it is possibly past it. Plywood these days seems to be what is used now for flooring.

RickW

252 posts

Ultimate Geek

# 959606 31-Dec-2013 15:51

timmmay: Research spray wall insulation carefully, I've heard stories of dampness. I've had it, and it's fine.

Putting polythene under the floor and under floor insulation made a HUGE improvement to the dampness in my house. Do it properly, stake down the polythene so it can't move, tape it to piles, etc. I'm not sure if it's the polythene or insulation that helped most, probably the polythene, the insulation didn't make much of a difference to warmth. New carpet with a thick underlay did as much.

Carpet could be musty too.

Yea I have been looking at spray foam for a while the reason for packing the walls out the extra 45mm is so that the dew point will be inside the the spray-foam which is is closed cell/a vapour barrier and therefore will (if my math is any good) eliminate basically all the moisture issues in the wall.

I thought the dampness under the house would be the main thing and I'm glad you had so much success with the polythene, I plan on tackling that later this week.

Yea the carpet was pretty musty smelling and was one of the first things to go in the skip so here's hoping that alone will go a long way to eliminating the damp smell.

I had a can of a oil based primer which I have just finished applying the first coat so here's hoping I don't have to go pulling up the chipbord.

RickW

252 posts

Ultimate Geek

# 959608 31-Dec-2013 16:02

mattwnz: For what you are doing, you will very likely need building consent. Spray insulation s also not common in nz, and from what I have read, it can shrink and create gaps, and am not sure how it is if it comes into contact with wires and pipes over the long term. . A wool type is possibly best, as it breathes, especially if you have moisture. I am not sure if the expense stagging wall studs is worth it, as a lkot of work and additional expense, and the council will probably want drawings and specs. Possibly better inside to have 140 thick framing and tick insulation. . Most heat is lost throught roof and windows anyway.
If you have old particle board flooring, and it is damp, it is possibly past it. Plywood these days seems to be what is used now for flooring.

I have checked with the council and since I'm not altering the structure of the house we do not need building consent for the walls.

The spray-foam that normally shrinks is the pre expanded type that you drill holes in the walls for, the contractor that I'm planing on using generally deals with commercial buildings but has done a few houses.

That's a good point regarding the pipes and power, there are no pipes in the external walls and I have run the purple cable. I can't remember what it's called, beside the tps ready for our sparkly to connect up when they start back up.

froob

521 posts

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# 960150 1-Jan-2014 23:35

One person supports this post

There is some useful information on retrofitting insulation at http://www.dbh.govt.nz/retrofitting-insulation-guidance. As was said in an earlier post, it seems very likely that you would need building consent for this work. From the linked page:

Schedule 1 of the Building Act now exempts underfloor and roof insulation retrofits from building consent. However, retrofitting insulation into a wall cavity is not exempt; it either requires a building consent or specific approval from a BCA that a building consent is not required.

The person you spoke to at the council might not have been totally up to the play with building consent requirements, or might not have completely understood the details of the work you're planning. The council probably has a formal process for granting building consent exemptions which you could go through. If they don't, my thoughts are that you would still want to get confirmation in writing to cover yourself off.

Edit: typos.

mattwnz

15210 posts

Uber Geek

# 960163 2-Jan-2014 00:35

froob: There is some useful information on retrofitting insulation at http://www.dbh.govt.nz/retrofitting-insulation-guidance. As was said in an earlier post, it seems very likely that you would need building consent for this work. From the linked page:

Schedule 1 of the Building Act now exempts underfloor and roof insulation retrofits from building consent. However, retrofitting insulation into a wall cavity is not exempt; it either requires a building consent or specific approval from a BCA that a building consent is not required.

The person you spoke to at the council might not have been totally up to the play with building consent requirements, or might not have completely understood the details of the work you're planning. The council probably has a formal process for granting building consent exemptions which you could go through. If they don't, my thoughts are that you would still want to get confirmation in writing to cover yourself off.

Edit: typos.

Agree, get it in writing from your TA, just in case.

Hammerer

2035 posts

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# 960196 2-Jan-2014 09:48

RickW: ...

Yea the carpet was pretty musty smelling and was one of the first things to go in the skip so here's hoping that alone will go a long way to eliminating the damp smell.

I had a can of a oil based primer which I have just finished applying the first coat so here's hoping I don't have to go pulling up the chipbord.

Have you actually got OSB (Oriented Strand Board) or cheaper particle / chip board? If the latter then I'd cut out a small part of the worst section and check it before painting over. I'd replace it if it's got black mould/mildew through it or is separating.