davidc

Wood Fibre

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Are there any notable drawbacks for going with wood fibre (blown in roof on site, sheathing in walls) for a timber frame construction ? (Previous proposition was Celotex but considering wood fibre for comfort factor).

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Ours is a wood fibre house.

 

100mm thick wood fibre board on all external walls and 100mm thick wood fibre board on the roof as a sarking board.

 

Originally we planned blown in wood fibre chips as the frame insulation until I discovered you get the same U value and nearly as good decrement delay using Earthwool Frametherm 35 for half the cost. And it was a DIY job to fit it not needing a gang of men with a blower machine.

 

The only "drawback" is what finish are you planning?  Ours is rendered direct onto the wood fibre board.  the first winter we had a problem with the bottom edge along the garage wall blew, we have had that bit re done.  We now think there is a blister on the gable end wall. Still need to get that looked at, but if the render is going to give trouble then that is obviously a big disappointment.  Don't know if it is "the system" or poor application, and expect everyone to blame everyone else.

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15 minutes ago, ProDave said:

Earthwool Frametherm 35

 

Completely off topic, sorry. If anyone is interested in how Earthwool is made, I found this video fascinating. I didn't know it comprises 80% recycled glass!

 

 

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Posted (edited)

thats video says GLASS wool --not earth wool --so earth wool is really glass wool -

Edited by scottishjohn

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Thanks, the finish will be timber (with no masonry leaf).

 

In most wood fibre use cases i have seen folk seem to have gone for rigid boarding non the exterior or blown into the frame - so is there any reason the batt type wood fibre isn't installed within the frame itself ?

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The problem with any rigid batt type material is getting a snug fit. Leave gaps and air can get past making the insulation very much less effective. That is where wool or blown in types win.

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@ProDaveas i'm still trying to save money, i'm now thinking whether i should go with the frametherm 35 as i can self install. i was going with 350mm blown cellulose for a u value of 0.1 but if i can achieve the same u value with the batts it would be sensible

 

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4 hours ago, ProDave said:

The problem with any rigid batt type material is getting a snug fit.

 

Isn't stuff like Frametherm flexible enough to get a snug fit anyway?

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14 hours ago, Simplysimon said:

@ProDaveas i'm still trying to save money, i'm now thinking whether i should go with the frametherm 35 as i can self install. i was going with 350mm blown cellulose for a u value of 0.1 but if i can achieve the same u value with the batts it would be sensible

  

 

I was hoping to use Cellulose in my I-beam frame but I just couldn't make the numbers work within our budget.

Instead I switched to 300mm of Rockwool bought at a decent price in bulk and saved a considerable amount. My recommendation if doing it again would be to look at getting the roof blown in Cellulose and do the walls yourself as a compromise in something like rock wool. Walls are easy, the roof was tedious as is any job working about your head.

 

The Rockwool seems incredibly dense and even with some openings not yet permanently blocked the house feels very soundproof with little temperature change throughout the day.

 

 

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9 minutes ago, bissoejosh said:

 

I was hoping to use Cellulose in my I-beam frame but I just couldn't make the numbers work within our budget.

Instead I switched to 300mm of Rockwool bought at a decent price in bulk and saved a considerable amount. My recommendation if doing it again would be to look at getting the roof blown in Cellulose and do the walls yourself as a compromise in something like rock wool. Walls are easy, the roof was tedious as is any job working about your head.

 

The Rockwool seems incredibly dense and even with some openings not yet permanently blocked the house feels very soundproof with little temperature change throughout the day.

 

 

Waving your arms above your head, like you are swatting wasps, trying to hold the bloody stuff up. Add to that the shoulder ache at the end of the day. All good fun if you have a wierd sense of humor.

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10 hours ago, Ed Davies said:

 

Isn't stuff like Frametherm flexible enough to get a snug fit anyway?

Yes Frametherm is perfect for the job. It is flexible yet stiff enough that when pushed in between the rafters of a roof, it just stays there.

 

My comment was about his suggestion to fill the frame with slabs of wood fibre. Those are not flexible enough to squash in.

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@Big Jimbo can I ask where did you get the rockwool from and what type was it? Were they any problems fitting it around the flanges of the IJoists. I have come to a similar conclusion as yourself-  Warmcell for the roof and DIY for the walls.  Trying to workout the best solution for the walls but have time to think as they are not up yet! 

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At the time I bought mine, SIG (Sheffield Insulation Group)  were by far the cheapest place to buy frametherm 35 from.

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4 hours ago, matt-shrops said:

Were they any problems fitting it around the flanges of the IJoists.

 

My building warrant says fitting round the I-beam rafters but I've had second thoughts on the matter. I'm now thinking to put 25mm EPS in the I-beam to get a flattish surface to stuff the mineral wool up against.

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Posted (edited)
5 hours ago, matt-shrops said:

@Big Jimbo can I ask where did you get the rockwool from and what type was it? Were they any problems fitting it around the flanges of the IJoists. I have come to a similar conclusion as yourself-  Warmcell for the roof and DIY for the walls.  Trying to workout the best solution for the walls but have time to think as they are not up yet! 

I purchased all my Rockwool flexi from https://www.ccfltd.co.uk/Rockwool-Flexi-Insulation-Slab-1200-x-600mm/p/9000218706

I had about 200 packs as my walls have 3 layers of 140mm, 70mm and 50mm. Really great product, very dense. Easy to fit and cut with a saw. 

If you are working at 600 or 400 centres all works well. Stays in place even in the rafters.

 

 

Edited by JamesP

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i know that 350mm of cellulse gives me a u value of 0.1, does anyone know offhand what 350mm of frametherm will give? save me working it out😎

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@ProDave where did you buy your woodfibre board from - I have had a look at SIG and don't think sell it, well not yet! 100mm stuff must be expensive but guess you saved using frametherm rather than warm cell?

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I bought mine through Carbon Dynamic, the company that did all the design work and drawings. They are local to us and they build modular houses in their factory.  They were the local agent for both the wood fibre board and the render system that we used and the prices I got from them were much cheaper than anywhere else I could find.  I guess the result of buying in bulk for their own use and selling it on with only a small markup.

 

Before you go rushing to find them, they went into adminstration just before christmas and subsequently were bought by another larger building company. Now that they are under new ownership I don't even know if they would sell materials directly. I have not had any dealings with them since the change of ownership.

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23 hours ago, Ed Davies said:

 

My building warrant says fitting round the I-beam rafters but I've had second thoughts on the matter. I'm now thinking to put 25mm EPS in the I-beam to get a flattish surface to stuff the mineral wool up against.

 

This is what a friend of mine did to get round the issue. Worked well, if a little time consuming, as a solution.

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does anyone know the difference in the decrement delay, didn't want to mention the 'tm' words. frametherm seems to be better than cellulose for u values, at least the 32.

@ProDave was there a reason for the 35 as opposed to the 32

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1 hour ago, Simplysimon said:

does anyone know the difference in the decrement delay, didn't want to mention the 'tm' words. frametherm seems to be better than cellulose for u values, at least the 32.

@ProDave was there a reason for the 35 as opposed to the 32

I probably didn't research the different options well enough at the time.  It was the builders that built the shell that recommended I used Frametherm 35 instead of blown in wood fibre, which was the original plan, and I never questioned the 35

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On 12/04/2019 at 15:53, Ed Davies said:

My building warrant says fitting round the I-beam rafters but I've had second thoughts on the matter. I'm now thinking to put 25mm EPS in the I-beam to get a flattish surface to stuff the mineral wool up against

Exactly what I did and it worked very well. Only my electrician was annoyed as he had to make sure his wiring didn't come into contact with the EPS.

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5 hours ago, Simplysimon said:

does anyone know the difference in the decrement delay, didn't want to mention the 'tm' words. frametherm seems to be better than cellulose for u values, at least the 32.

@ProDave was there a reason for the 35 as opposed to the 32

 

I used 32 in my floor and 35 in my wall. The difference in the two was really evident. The 35 can be easily peeled but the 32 is much more dense.

 

On reflection I would probably have used 32 in the walls as well. 

 

 

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