Roof Insulation Installation

[The Grumpy Triker]

Hi all,

Hopefully a quick question, although judging by other threads on the topic it may not be.

I'm replacing the internal ceiling (sorry can't remember the proper name for one on a boat) & the old packing foam style insulation in the boat as it is all a bit tatty and I have a few leaks.....plus when I get the stove installed I think it would be wise not to burn the inside.

I think I have to use rockwool as celotex doesn't look like it will bend with the roof shape but either way.....Do I need to prime the inside of the steel before putting in the insulation?and is it worth putting a thin layer of insulation over the wooden battens before putting in the new ceiling? (I don't have the option of spray foam or anything like that for now.)

Lovely snow scene outside here....not much to do except for keep ripping the boat apart 

[koukouvagia]

Instead of Rockwool, which is floppy and difficult to fix to a ceiling, why not use slab insulation?  This is designed to be wedged tight between battens. You will need a vapour barrier.  I used plastic sheets stapled to the battens.

I know not everyone likes Thinsulate, but I've got this in our newly renovated back cabin and there's not the slightest trace of condensation.  This is also easy to fix; you just use contact adhesive.

 

[The Grumpy Triker]

13 minutes ago, koukouvagia said:

Instead of Rockwool, which is floppy and difficult to fix to a ceiling, why not use slab insulation?  This is designed to be wedged tight between battens. You will need a vapour barrier.  I used plastic sheets stapled to the battens.

I know not everyone likes Thinsulate, but I've got this in our newly renovated back cabin and there's not the slightest trace of condensation.  This is also easy to fix; you just use contact adhesive.

 

Being a bit dim on this front, the vapour barrier goes steel side or room side of the insulation?

not heard of thinsulate before..?...am assuming it bends with the roof shape?....what is it that people don't like about it?

Was going rockwool way as didn't think the block insulation would bend enough...hence why I'm calling on the knowledge of the Cutting Crew

Many thanks for such a prompt response 

[alan_fincher]

8 minutes ago, koukouvagia said:

Instead of Rockwool, which is floppy and difficult to fix to a ceiling, why not use slab insulation?  This is designed to be wedged tight between battens. You will need a vapour barrier.  I used plastic sheets stapled to the battens.

I think it depends on what you mean by "Rockwool", which is really a brand name, rather than any specific product.

I don't think the term just relates to stuff on a roll, for loft insulation, does it?

I think some slab insulation is also called "Rockwool".

But yes, I agree, use slabs, which can generally be persuaded to wedge in until lined over in whatever material you choose.

The only thing I would say is that you may need to compress them a bit.  In "Flamingo" the polystyrene we removed was only a disappointing 25mm thick, (no doubt part of why it takes some heating!).  We have replaced with 50mm wool slabs, but into a gap that is often not quite 50mm.

What OP has not mentioned is what goes between insulation and ceiling.  I think common wisdom is to put a plastic membrane in, although in our last professionally fitted boat there was none, and we never had any problems because there wasn't one.

[The Grumpy Triker]

2 minutes ago, alan_fincher said:

I think it depends on what you mean by "Rockwool", which is really a brand name, rather than any specific product.

I don't think the term just relates to stuff on a roll, for loft insulation, does it?

I think some slab insulation is also called "Rockwool".

But yes, I agree, use slabs, which can generally be persuaded to wedge in until lined over in whatever material you choose.

The only thing I would say is that you may need to compress them a bit.  In "Flamingo" the polystyrene we removed was only a disappointing 25mm thick, (no doubt part of why it takes some heating!).  We have replaced with 50mm wool slabs, but into a gap that is often not quite 50mm.

What OP has not mentioned is what goes between insulation and ceiling.  I think common wisdom is to put a plastic membrane in, although in our last professionally fitted boat there was none, and we never had any problems because there wasn't one.

Thanks Alan....I know you have the membrane in an attic roof space but wasn't sure what happened with steel....do you stick the membrane to the steel or just have it wedged between the 

Just taken down the polystyrene in the roof (same as yours only 25mm and not all over) and realised there are no battens in the middle.....large thin sheeting x 2 in an overlapping was just stuck to the above and wedged between two side battens for good measure.

There are a couple of cross beams but not what I expected.

This could be fun now 

[OldGoat]

Celotex will take a slight amount of bending (at least it did when we built or log cabins last year) If you're worried, 2 x 25mm is more flexible than 1 x 50mm. On the boat - so long ago I use polystyrene which is not dissimilar in construction to Celotex.  It all depends on what sort of curvature you have in the roof. 

Reading your latest post - yes there will be challenges, but despite your lack of cross beams you have a large surface area and modern adhesives can be magical....

[Sea Dog]

49 minutes ago, The Grumpy Triker said:

I'm replacing the internal ceiling (sorry can't remember the proper name for one on a boat)... 

It's "deck head", but if you have a scouse accent you'd be as well to keep calling it a ceiling! 

[The Grumpy Triker]

1 minute ago, OldGoat said:

Celotex will take a slight amount of bending (at least it did when we built or log cabins last year) If you're worried, 2 x 25mm is more flexible than 1 x 50mm. On the boat - so long ago I use polystyrene which is not dissimilar in construction to Celotex.  It all depends on what sort of curvature you have in the roof. 

Reading your latest post - yes there will be challenges, but despite your lack of cross beams you have a large surface area and modern adhesives can be magical....

That's a good point on the half thickness - thanks....will have to ski to B&Q and test out the bend ....I think they have Celotex.

The gluing bit again makes sense (no major issue as you say but just not as expected son initial plans need amending), just wondering about the bond to the membrane an onwards to roof....unless I glue to roof and then fix membrane under that?...yep I know, will be a bloody daft question to many 

1 minute ago, Sea Dog said:

It's "deck head", but if you have a scouse accent you'd be as well to keep calling it a ceiling! 

[BEngo]

If you use PU foam slabs they are non-porous and foil faced so contain most of the vapour barrier provided you don't damage the foil facing.  Tape over the joins and any nicks  with aluminium foil tape so the steel is all covered and that's the job done.  It is well worth putting thin insulation on the battens if you can get some.

 

N

[The Grumpy Triker]

29 minutes ago, BEngo said:

If you use PU foam slabs they are non-porous and foil faced so contain most of the vapour barrier provided you don't damage the foil facing.  Tape over the joins and any nicks  with aluminium foil tape so the steel is all covered and that's the job done.  It is well worth putting thin insulation on the battens if you can get some.

 

N

Thanks BEngo

I think the one thing I'm most concerned about will be the stove chimney...does it need special insulation or given a twin skin flu are most insulators fire safe?....or will that need something like rockwool surrounding it?

[ditchcrawler]

This is not a job I have done but I have seen others and in those cases what I saw was steel with the insulation hard against it and then a pvc vapour barrier followed by the lining. It was suggested to me that the use of thin polystyrene that is made to go under wall paper between the face of the batten and the lining. I would also put glass wool around where the flue goes through for about a square foot

Edited December 10, 2017 by ditchcrawler

[haza]

why not use kinspan thats the best 

[OldGoat]

32 minutes ago, haza said:

why not use kinspan thats the best 

Or even Kingspan (sorry) If possible avoid B&Q or the like - find a proper builders' merchant for better quality

[The Grumpy Triker]

1 hour ago, ditchcrawler said:

This is not a job I have done but I have seen others and in those cases what I saw was steel with the insulation hard against it and then a pvc vapour barrier followed by the lining. It was suggested to me that the use of thin polystyrene that is made to go under wall paper between the face of the batten and the lining. I would also put glass wool around where the flue goes through for about a square foot

Thanks DC

3 minutes ago, OldGoat said:

Or even Kingspan (sorry) If possible avoid B&Q or the like - find a proper builders' merchant for better quality

I was told it wasn't too flexible so may not fit the curve in the roof and looked expensive....but may not be looking at the right product on their website

[WotEver]

13 minutes ago, The Grumpy Triker said:

I was told it wasn't too flexible so may not fit the curve in the roof and looked expensive....but may not be looking at the right product on their website

It isn’t. But as others have said, two 25mm is a lot more flexible than one 50mm. 

The vapour barrier normally goes on the House side of the insulation. So in your case it’s roof, insulation, vapour barrier, cladding. 

[koukouvagia]

This picture shows how the slab insulation is wedged in between the battens and how the vapour barrier is fixed.  

This has been in place for over ten years and shows no sign of deterioration.

[Robbo]

Advantage of rock wool slabs is that it is good at sound insulation as well (I have rockwool on top of sprayfoam, and I got the rockwool purely for sound insulation properties).   Rockwool isn’t as good as Kingspan for insulation tho.  I used underfloor foam boards as a thermal barrier for between battens and the hull.

[The Grumpy Triker]

Many thanks all....I knew this wouldn't be a quick one 

...more choices and a bit of pondering required.

[cuthound]

My boat is insulated with 3M Thinsulate. It is a flexible fabric,  which is stuck directly to the steel.

In my opinion it is very good, better than rockwool or Celotex/Kingspan (which lose some of their insulation properties as the gas trapped within the cells rates over time), but not quite as good as well applied sprayfoam.

It has much better noise insulation properties than sprayfoam.

http://www.sikaflex.co.uk/thinsulate

Edited December 10, 2017 by cuthound

[D. W. Walker]

There is a website called Insulation Seconds that sells off cuts, seconds, over productions etc of insulation. Mainly Kingspan and Celotex, good prices etc, (I've no connection with them)

[The Grumpy Triker]

13 hours ago, cuthound said:

My boat is insulated with 3M Thinsulate. It is a flexible fabric,  which is stuck directly to the steel.

In my opinion it is very good, better than rockwool or Celotex/Kingspan (which lose some of their insulation properties as the gas trapped within the cells rates over time), but not quite as good as well applied sprayfoam.

It has much better noise insulation properties than sprayfoam.

http://www.sikaflex.co.uk/thinsulate

Many thanks Cut  ...is there a specified thickness or a choice?.....if a choice what did you have fitted?

11 hours ago, D. W. Walker said:

There is a website called Insulation Seconds that sells off cuts, seconds, over productions etc of insulation. Mainly Kingspan and Celotex, good prices etc, (I've no connection with them)

 Many Thanks DW will have a nose for sure

[cuthound]

18 minutes ago, The Grumpy Triker said:

Many thanks Cut  ...is there a specified thickness or a choice?.....if a choice what did you have fitted?

Mine was already on the boat when I bought it. The boat was advertised as having rockwool insulation. 

I specifically asked the surveyor to check, and he found 3M Thinsulate.

Not sure how thick as it is stuck to the steelwork behind wooden panelling. Perhaps 25-50mm?

There is some loose Thinsulate over the stainless steel tanks, that is around 25mm thick.

If you call Sikaflex using info from the link I provided I am sure they will tell you what thicknesses are available.

Edited December 11, 2017 by cuthound
To unmangle the effects of autocorrect.

[Robbo]

14 hours ago, cuthound said:

My boat is insulated with 3M Thinsulate. It is a flexible fabric,  which is stuck directly to the steel.

In my opinion it is very good, better than rockwool or Celotex/Kingspan (which lose some of their insulation properties as the gas trapped within the cells rates over time), but not quite as good as well applied sprayfoam.

It has much better noise insulation properties than sprayfoam.

http://www.sikaflex.co.uk/thinsulate

If I was re-doing insulation, I would seriously be investigating thinsulate.   How good is it at Sound Insulation?

[cuthound]

1 hour ago, Robbo said:

If I was re-doing insulation, I would seriously be investigating thinsulate.   How good is it at Sound Insulation?

It's great for sound insulation. Much better than sprayfoam in that respect.

[The Grumpy Triker]

4 hours ago, cuthound said:

Mine was already on the boat when I bought it. The boat was advertised as having rockwool insulation. 

I specifically asked the surveyor to check, and he found 3M Thinsulate.

Not sure how thick as it is stuck to the steelwork behind wooden panelling. Perhaps 25-50mm?

There is some loose Thinsulate over the stainless steel tanks, that is around 25mm thick.

If you call Sikaflex using info from the link I provided I am sure they will tell you what thicknesses are available.

Cheers again.

i quite like this option as I have a few protruding screws/rivets on the inside of the roof which would immediately pierce any condensation barriers on a slab material......would it really make a difference?....I don't know but given the option like this it seems a good option.

The old styrofoam of some sort was held on by something with the consistency of a bathroom sealant and have got rust areas (thin) on all areas of the application....and fun at this time of year is that every morning the condensation is like a rain shower where I've stripped the insulation.....helped by a few leaky screw holes as well 

All of which keeps me busy and doing my project....want it finished before next summer but will have to be patient on all fronts.