Another Renotherm question....!

[Simon Hawthorne]

Hello all

I've ben trawling through the hundreds of posts here over the last 3 years - all discussing Renotherm.

I have had a couple of quotes for sorting out my barn roof - the best coming in at around £6k. Ronotherm man has just left - and has quoted me £6k to spray it! As part of the job, they'll straighten up any of the tiles, replacing as necessary, make sure the roof is watertight and then spray away. I know the roof timbers are good - and really want to keep the rafters visible - which I would lose if I just had the roof removed/rebuilt then used ordinary insulation and plasterboard.

What do you guys think? He also quoted me on doing the house roof, the walls of the barn and the ceiling space between the two floors in the barn (this was my request more as a means of soundproof than insulation...)

Would be really grateful for any thoughts, comments....

Thanks

Si

[Owain]

"Simon Hawthorne" wrote | I have had a couple of quotes for sorting out my barn roof - the best | coming in at around £6k. Ronotherm man has just left - and has quoted | me £6k to spray it! As part of the job, they'll straighten up any of | the tiles, replacing as necessary, make sure the roof is watertight | and then spray away. I know the roof timbers are good - and really | want to keep the rafters visible - which I would lose if I just had | the roof removed/rebuilt then used ordinary insulation and | plasterboard.

Well, you're also going to lose the visible roof timbers if you renotherm aren't you.

Why not remove the slates, battens and sarking, and replace with SIPs (Structural Insulating Panels) over the existing timbers. That way you keep the visible roof timbers inside and also get nice insulation.

| What do you guys think? He also quoted me on doing the house roof, | the walls of the barn and the ceiling space between the two floors in | the barn (this was my request more as a means of soundproof than | insulation...)

Don't know whether it would be possible to use SIPs on the walls of the barn. Renotherm or anything else foamy is unlikely to provide much in the way of soundproofing between floors.

Owain

[Grunff]

Will they really...

From what I've seen/heard, the treatment is nothing like the description. They simply turn up, spray, and go away. This will in the short term fix any possible leaks, so will leave many people satisfied. But it really isn't a good long term solution.

How bad is the roof? Either it needs replacing or it doesn't - renotherm or not. If it needs replacing, then the only long term solution is to replace.

I've looked at the photos on your site, but they don't really show enough.

[Simon Hawthorne]

Thanks for your reply. I'd always considered I would have to remove the roof to fix one of the walls, which is bowing out a little - and to replace some of the laths - which although not rotten, have slipped

- something to do with the nails....? Having spoken to a few more people, the wall can be fixed with props holding up that section of the roof is necessary, and the low beam that I would like moving up about 12 inches, again can be done with only a little work on that part of the roof. Overall, the roof timbers are in good nick - it has always been me that has assumed removal was the best course.

My quotes so far have all been without insulation - so Renotherm reckon if I do the brickwork and hire the beam, they will do the rest, including fit 4 velux style windows. The guy reckoned they are a roofing company - not just the 'sprayers' I'd assumed. He had lots of pictures of work they'd done on similar buildings - and to be honest, I liked the look of them - and the fact I could keep my rafters visible and conform to building regs.

I just asked the question because my search of usenet has found that to every 1 person singing the praises of the spray solution, another 5 warn against it - although these people have not got first hand experience - they al just know someone who knows someone... if you get my drift....

So, in conclusion, I have got to do some brickwork and raise a beam. Then I either renotherm it OR have it stripped, feltted and the tiles replaced, and then pay more to have it insulated, which will mean I lose the rafters because they will be covered in plasterboard (they are not very thick) and of course, add more weight to my already suspect footings!

Regards

Si

[G&M]

Do the job properly or not at all. Sticking the roof together with sticky foam isn't a good move as it's nearly impossible to fix again later.

[Grunff]

I am indeed one of those people (though I don't believe I've posted on the subject before).

This is the bit that puzzles me - I don't understand why it's a choice between these two things.

If the slates are good, then they don't need stripping. If they aren't good, then the roof should be reslated regardless of whether or not you're going to renotherm it.

Otherwise you will be relying on the renotherm to provide waterproofing as well as insulation - I don't believe this is a good strategy.

I have two main objections to sprayed-on roof insulation:

[a] what happens when you need to replace a slate in 5 years time? Slates do and will sometimes break. [b] since you'd be relying on the foam for waterproofing, this suggests that some water will get in behind the foam. What will this do to the wet side of the timber?

[Simon Hawthorne]

Ok... don't think I have made myself very clear. The tiles are all ok

- a few loose and missing - but an easy fix. There is no felt - although the roof is watertight. I will have a little building work done around the roof - including a wall rebuilt, a main roof timber raised and some lathing repaired. This will be done regardless...

My choices are...

1 to comply with building regs I will have to take all the tiles off to lay felt (there is none now - even though it is watertight). Then I will have to insulate and finally plasterboard it...

or

2 Get it sprayed to provide the insulation I require and retain the use of the rafters

Seems to me the issues around spraying roofs are if it is in a poor state initially... If it is sound, then what are the problems...?

Thanks again

Si

[Grunff]

Says who? Our roof isn't felted. Or does this count as a barn conversion?

[Simon Hawthorne]

Sorry, I meant that it has to be insulated either way......wasn't reffering to the felt....

[Simon Hawthorne]

Nope - the rafters aren;t very deep - so I am led to believe that to fill between them with ordinary insulation would be so deep that toy would end up fitting palsterboard to the rafters - effectively losing them. The spray would sit in between them, leaving just enough for them to be a feature.....

S.

[Andy Hall]

The difficulty comes if you want to sell it. This process prevents the roof from being inspected in the future and has become associated in a lot of people's minds with bodging a roof in poor condition in older houses. I wouldn't go as far as to say that it would make the place unsaleable, but there are certainly buyers who would walk away. Unfortunately bad associations are difficult to overcome.

.andy

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[Peter Taylor]

Simon Hawthorne wrote

The reason why so many people don't have first hand experience of Renotherm is because they are smart enough to know it's a bodge. Like so-called lifelong wall coatings, it's a classic case of finding a use for a material, rather than finding a material to do a particular job.

I've deliberately waited to see others' views, but I totally agree with what everyone has said and for the same reasons, particularly Grunff. Ten to one if you stripped the roof now you would find it's in a far worse condition than you think. If you Renotherm it you'll still have the same old slates, nails and battens, lead flashings and mortar pointing and when the time comes to renew or even repair these it will be a terrible job. The insulation will not be continuous over the rafters, there is greatly increased risk of rot damage and I'm sure Owain is right about the foam covering the rafters (where else can it go?). Don't do it Simon.

Anyway, £6K sounds quite low value for what they will be doing and what you'll end up with. I think you should be looking at what else you could get for that sort of money. I would certainly consider stripping and refixing the existing slates, whatever condition they're in now. There will definitely be some which are unusable and you'll need a percentage of make-up reclaimed slates, but they would have needed replacing soon anyway. The great advantage of doing this is you can create a proper warm roof with continuous Celotex type insulation over the top of the rafters, with no risk of condensation or rot damage. Also there will be no mucking about fitting Veluxes and flashings and trying to make good to the existing slating and you will have nice new lead flashings and mortar pointing. It's got to be worth doing.

Peter

[Andy Hall]

I think that this is sound advice.

I was faced with a similar situation in a property that I had some years ago. There was quite extensive wet rot/weevil damage around a valley between two roof sections which was not apparent until the slates were removed.

Once they were, fixing the problem was relatively simple because there was good access. It was also possible to have the battens replaced, felt added and the timbers thoroughly treated.

The builder allowed for about a 50% replacement of the slates because some were in good condition while others were cracked or spalled.

For the peace of mind of knowing that the roof is sound and there are not hidden nasties, if that cost £10k rather than £6k I would do it. However, there may not be as much difference as one might imagine,.

.andy

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[G&M]

Why do you need to lay felt ? Lots of old properties have no felt. Kingspan insulation with a 50mm gap from the tiles meets the regulations on insulation.