HELP! Loft chipboard flooring rot..

[Smileysmile]

I moved into a newbuild (2001) 3 years ago and temporarily layed a few b and q 18mm chipboard panels (comes in pack of 3) just to hold a few boxes until I had sorted out rest of house. I must have layed about 10 across the joists and never returned until 3 yrs later finally decided to lay the middle part of the loft with chipboard panels again bought from B & Q pack of 3.

Firstly I widened the hatch with a built in drop door.

When I came to remove the boards I put down 3 yrs ago they had turned very pale and light as a feather AND easy to snap!! Whats going on? They are identical to the ones I have just bought. I had 3 of the orginal ones standing up in my spare bedroom and they were fine.

Can I say I layed the loft with the same boards in the house I lived in 10 years ago and I had no problem. When I layed them they were still looking good 10 yrs later and withstood my weight when walked on.

I have placed about 20 boards down, staggered, and various cuts to fit across the joists. Butted them together and screw them into joists. I am very pleased with my work. But now I am so worried that over a short time now they are going to end up like the previous ones I put down.


Heeeeeeeeeeeeeeeeeeeeeelp!!! What can I do to prevent this from happening to my hardwork? What was the cause of this?

 

[big-all]

i assume they have got damp and disintegrated quite normal in an attic thats why you need to use water resistant boards

 

[Smileysmile]

Well why are they loft panels? They are specifically for the loft. Says on the package.
How is my attic damp? Never had problems with these panels in my house a few years back.
I think you will have to be more helpful than that

Maybe I should take them back and get my money back then??

 

[JohnD]

A 2001 house has probably got a felted roof, and possiby not much ventilation. If there is much humidity in the house, for example caused by draping wet washing over radiators; and/or warm humid air leaking into the loft, e.g. through holes for downlighters or pipes, then the roof space will be prone to condensation.

And especially if there is no ventilation space between the loft insulation and the chipboard, then the first cold surface the humid air meets will be the chipboard, so it will get condensation on it and become damp. Chipboard is a rubbish material anyway and falls apart from damp or wet. However it is cheap.

 

[Smileysmile]

this is not what I want to hear
Ok I will have to rip it all up then. What is the alternative?

The loft acts as a good storage place. So has to be done properly.
It took me 2 days.

I don't know whether to cry or not

 

[JohnD]

there may be a better way to do it

please describe the construction of your roof timbers - are they trussed rafters with a "W" shape?

what is the depth of the timbers you will be laying the floor on? and what spacing?

what insulation have you got? how thick?

what ventilation does the loft have? is it felted?

have you got holes in the ceilings e.g. for downlighters?

do you drape wet washing about the house?

do you use an extractor fan during and after every bath and shower?

 

[Smileysmile]

Blimey thats a mouthful! lol

Its a newbuild (Bellway) 2001.
Felt is on the ceiling of the attic.

The rafters are not unsual. Like a W I guess.
The insulation is that pink itchy stuff. Rockwool?
Which is fitted between the joists and slightly above them when they are puffed out.
I don't have downlighters in the house yet I dry my clothes on a huge 'clothe horse' in the kitchen. Never on the radiators.

I did this in my previous house built by Westbury. That was new in 1993 and similiar to this house and I had no problems. Maybe some ventilation in the attic is blocked. How the heck would I know if it is? I know I shouldn't have a problem with these boards. I am bemused!

 

[JohnD]

if there is no other vent that you can see, the loft may be ventilated by a gap at the edge, between the roof and the wall. See if this has been blocked, usually (wrongly) with insulation. You should be able to see daylight and/or feel a constant draught. If there is a gap at each side of the house, there should be a crossflow of air.

it sounds like your boards were pressed tight on the insulation. this prevents any ventilation so ecourages condensation which cannot dry out. it is usually recommended that you have an inch or two clear space that the draught can blow through.

one method is to cross-batten with timbers, say 50mm x 50mm, and put your boarding onto them so there is a ventilated airspace. Another newer method is to lay slabs of rigid insulating foam on top of the timbers, and put your flooring on top of that. You will find a display and leaflet in the DIY sheds so you can see what mean. The stuff they sell for the purpose is pink rigid foam, in small pieces. I suspect the white polystyrene slabs would work nearly as well. You can probably manage to get an 8x2 board through the hatch and between the trusses, I just can. If so it will be cheaper than small slabs; so will an 8x2 piece of chipboard work out cheaper than those little loft panels. I have just got enough strength and agility to get one through the hatch, you may be fitter than me.

 

[Smileysmile]

I shouldn't have to put timber on top of the joists and then boards over them.
Are you absolutely certain That air has to flow between boards and insulation?
If that is so then maybe I can replace just the insulation under the boards with alternative insulation ie slabs that fit between the joists which don't quite reach the top of the underside of the boards to allow 'breathing' and 'airflow'.

What do you think?

 

[JohnD]

Are you absolutely certain That air has to flow between boards and insulation?

yes
if it is ordinary loft insulation (glassfibre or mineral wool) as it is not airtight so moisture can rise through it.


with the foam slabs, as long as they are tightly fitted with no gaps and sealed joints, you can put the board direct on top.

 

[Smileysmile]

so in a nutshell...lift the boards up and remove ALL the pink itchy insulation and replace with these slabs which I take will need cutting to fit tightly between the joists?

Maybe I should call a local insulation expert as this is important to me and I don't wish for these boards to crumble on me mths down the line

 

[JohnD]

if it was me I'd put the slabs on top of the timbers, like I said, and not take up the insulation.

I also saw some loft flooring chipboard ready-bonded to insulating slabs in B&Q the other day.

I think it was on clearance so might be being discontinued.

 

[Smileysmile]

I am stressed!

Why do B & Q sell these panels if their is more to it than just laying them on top of your joists and screwing them down?

I still can't believe I had no problems with my old house with this same procedure. Maybe the ventilation is blocked? It gets very hot in the loft in the summer

 

[JohnD]

hey buddy, life's like that. Only women moan. Just let it wash over you.