Attic Insulation

hot to trot

Dormer attic spaces and a top of house attic to insulate. Nothing in either space.

Have decided to lay rolls on floors between and on top of joists and tack bubble silver stuff to rafters. Think this might be the most appropriate? Possibly too many pipes for spray stuff.
What do I do with the upright walls that back onto the bedroom space ( ie behind the headboards. Do I put floor stuff between the upright joists and tack them in , or am I completely going about this the wrong way.

Am mithered trying to sort it all out.

Carlow52

what material is used as 'roofing felt' along the rafters under the tiles/slates?

hot to trot

There seems to be black stuff that looks like heavy sacking . Its hanging down in a few places

Carlow52

So if we look at the problem as 3 sides of a right angled triangle and you are contemplating insulating all 3.

The sloped roof [hypothenuse] is where u are putting the bubble foil
the base is where the 2 layer of glass fiber and the perp height is the upright walls.

IMO it makes no sense to do all 3:
u either do (the base and perp h) or (the hypothenuse) and if you do the hypothenuse u will also need to do the gable ends if roof not hipped.

However I am interested to see what the experts think here.

The bubble foil is not a breathable product so it will not allow your house to breath and you will have condensation problems.

Also its pretty crap as an insulation on its own: it does act as a good airtight membrane which is prolly why u are contemplating using it because of the tears in the felt

If u want to do the hypothenuse then consider a breathable insulation such as wood fibre across the rafters: however the tears in the roof felt will risk it getting wet.

However there are some that are rain resistant, it can be explored if you are interested and the experts reckon the mission is a go:)

My final questions are
what insulation is in the roof along the slope of the bed room before the roof goes horizontal again -your top of house?

are ur soffit boards ventilated?

hot to trot

Carlow52 wrote: »

So if we look at the problem as 3 sides of a right angled triangle and you are contemplating insulating all 3.

The sloped roof [hypothenuse] is where u are putting the bubble foil
the base is where the 2 layer of glass fiber and the perp height is the upright walls.

IMO it makes no sense to do all 3:
u either do (the base and perp h) or (the hypothenuse) and if you do the hypothenuse u will also need to do the gable ends if roof not hipped.

However I am interested to see what the experts think here.

The bubble foil is not a breathable product so it will not allow your house to breath and you will have condensation problems.

Also its pretty crap as an insulation on its own: it does act as a good airtight membrane which is prolly why u are contemplating using it because of the tears in the felt

If u want to do the hypothenuse then consider a breathable insulation such as wood fibre across the rafters: however the tears in the roof felt will risk it getting wet.

However there are some that are rain resistant, it can be explored if you are interested and the experts reckon the mission is a go:)

My final questions are
what insulation is in the roof along the slope of the bed room before the roof goes horizontal again -your top of house?

are ur soffit boards ventilated?

Thanks for all your input,its a great help.
The reason I was thinking of doing the entire triangle was :

• I was going to do the base/floor to stop the heat escaping from the rooms below.
• I wanted to do the upright /h to stop the heat transferring sideways from the bedrooms.
• I had seen on the B&Q youtube videos about the silver bubble wrap to reduce the cold coming in from outside and to reflect anyinside.

Because it is stapled onto the rafter joists there is loads of room to circulate air behind it . Certainly a lot more than is allowed for in one of the previous posts where they install plastic stuff and then foam over it . I take your point about it not being breathable , so perhaps thats not a good idea. What is it supposed to be used for then ?

This woodfibre board. Would that be something like the Gutex stuff? Do you have to cut this to fit between the rafter joists Or do you just nail it over the ends of the joist beams? Should I try to get the felt repaired?

Would this board be good for the vertical upright as well and do I nail or screw it onto the uprights joists?

I dont know what is in the upper attic on top of the bedrooms but I dont think there is anything in there either. Have a new ladder so will go up tonight and check it out.

The gables are bare block in the atttics. Should I be covering them with something? Maybe this fibreboard stuff?

Sorry dont know what soffit boards are .

Carlow52

will get back later with a more detailed reply, however can u tell us what insulation if any is above the plaster board in the bedroom along the slope?

BryanF

hot to trot wrote: »

• I had seen on the B&Q youtube videos about the silver bubble wrap to reduce the cold coming in from outside and to reflect anyinside.

.

can you put up a link to this? silver bubble wrap, sounds dodgy, id like to see it and look at the IAB cert before commenting further..

Vanbis

BryanF wrote: »

can you put up a link to this? silver bubble wrap, sounds dodgy, id like to see it and look at the IAB cert before commenting further..

Plenty of videos on Youtube if you just search using "B&Q attic insulation".

BryanF

Vanbis wrote: »

Plenty of videos on Youtube if you just search using "B&Q attic insulation".

yep its as i thought their selling the foil stuff as an insulation product, here's my humble opinion on the stuff http://www.boards.ie/vbulletin/showpost.php?p=75127556&postcount=2

hot to trot

Carlow52 wrote: »

will get back later with a more detailed reply, however can u tell us what insulation if any is above the plaster board in the bedroom along the slope?

Went up to the upper attic at lunchtime. There is yellow fibreglass stuff about 3/4 depth of the joists up there. I presume that this is tucked in at the ends to meet up with the lower attics.
I counted the joists , so will also get something to lay on top of this existing yellow fluff up there. There is definitley a breeze blowing across it . The spiders were swinging away on their webs.

MicktheMan

hot to trot wrote: »

Went up to the upper attic at lunchtime. There is yellow fibreglass stuff about 3/4 depth of the joists up there. I presume that this is tucked in at the ends to meet up with the lower attics.
I counted the joists , so will also get something to lay on top of this existing yellow fluff up there. There is definitley a breeze blowing across it . The spiders were swinging away on their webs.

You have a cold roof construction. This breeze is important to keep your roof timbers dry. Attached below is a rough sketch of your options on how to insulate/airtight your roof. Remember insulation doesnt do airtightness and airtightness doesnt do insulation. Both are required to stop the heat from escaping

Carlow52

OP: in the sketch provided by MTM he has the word insulation and a line in figure 1 alonged the sloped part of roof.

If your roof set up is like the sketch, what existing insulation is provided along that section?
Is it stuffed with glass fibre?

hot to trot

That seems to be the construction of the roof all right. IN fig 1 , I can access the lower attics but I cant really assess what is there between that and the upper one. I suspect there is some yellow insulation stuffed in there along that diagonal.
My plan was to insulate as in figure one so that the bedrooms wouldnt lose their heat , as they would in figure 2. Not sure what material is best for the vertical bits. Should I be getting fibre board and cutting 50-60 lengths of it , or just try to stuff it with fluffy stuff?

If I insulate that doesnt sort the airtightness issue - but is it not supposed to be able to breathe to stop condensation?

MicktheMan

hot to trot wrote: »

If I insulate that doesnt sort the airtightness issue - but is it not supposed to be able to breathe to stop condensation?

You are right, insulation does not solve airtightness, and in my experience, airtightness is by far the most significant mechanism of heat loss in your case.

The airtight layer is always on the warm side of the insulation. The makeup of the wall, roof etc should consist of materials with increasing vapour diffusion openness as you go from inside to outside, i.e airtight layer is less diffusion open than insulation. This will ensure that there is little risk of condensation causing any issues in the roof structure.

Carlow52

What follows is an attempt to tease out some issues here that will elicit some considered replies from the experts
==
In this case one has to take a view on the a/t-ness of the plasterboard (pb) walls, and the pb ceilings from the rooms below.

For the walls, if you determine/decide the pb is not sufficiently a/t then one option is to put an a/t layer on the exposed (inside attic space) vertical supports and then add some form of rigid insulation: eg wood fibre.

This would mean that the dew point should occur in the wood fibre board but on the cold side of the a/t layer.

I would not recommend filling the air space created by the uprights in this case as the a/t layer must be on the warmest side.

==
If on the other hand you take the view that the a/t-ness of the pb is good enough then the airspace can be filled with insulation and the wood fibre added in sheets across the uprights.

==
The thing that concerns me a little here is if the insulated slope is stuffed with glass fibre as it will stop the air from the soffit vents passing across through the roof. In this case the tears in the existing felt could be a bonus:)

To reduce the 'draftiness' of the lower attic spaces one could consider putting a layer of woodfibre board along the inner surfaces of the rafters, however the final design will depend on the soffit venting.

In most houses where pvc soffits have been retro fitted, the vents are provided every so often.

In some new builds the vent is a continuous vent all along.

In the first case here the vents every so often will mean that not every space between the rafters will be vented so fitting the fibre board will need to cater for that.

Ther are a few ways of doing this which we can revisit if of interest.

My intuition tells me that reducing the draftiness with a thin layer of breathable insulation is a good idea in the case of a windy felted roof so I would some thoughts here.

hot to trot

Lots to think about here. Will get a longer ladder and climb right up to top and see what exactly is going on between the two attics. The engineers report I got when buying the house must also have information on it.
Will get bacvk to you .Thanks for this vital info.

hot to trot

Thanks for all your help and advice. What I did in the end , was to put isover - METAC in the upright plaster board that backs onto the bedrooms. It was a fairly stiff glass wool roll that you squeeze in and it stays put. then I put 150mm glasswool between the floor joists and then 200mm of knauff loftwool on top of this . I finished the top attic with the loft wool as well.
Having spent over 40 hours in the attics there seemed to be independednt air coming into the lower attics through cavity spaces and through ajoining spaces . same with upper attic. So even though they seem to be unconnected from the point of view of venitialtion , they seem to be independently aired.
I left under the tank clear and didnt have enough 3/4" insulation for the bigger pipes. So mainly the 1/2" ones are done.

Does this sound about right before I dump my goggles and mask and gloves

paddy147

BioFoam Open Cell 800.

Spray the fcuk out of the attic with it,gable walls too.

Job done.

I did both the attic spaces with it,and its the mutts nutts.

Neilw

paddy147 wrote: »

BioFoam Open Cell 800.

Spray the fcuk out of the attic with it,gable walls too.

Job done.

I did both the attic spaces with it,and its the mutts nutts.

Was this the company you used Paddy?

http://www.fusioninsulation.com/

paddy147

Neilw wrote: »

Was this the company you used Paddy?

http://www.fusioninsulation.com/

Nope,not them.

Neilw

paddy147 wrote: »

Nope,not them.

Any chance of telling us who you used then?

paddy147

Neilw wrote: »

Any chance of telling us who you used then?

Not here,because I got lifted out of it and banned from the forum before,because a certain moderator took "personal issues" with me naming the company.
He rekoned that I must be working for them or have some link to them,when I clearly dont,as I work in IT and dont have anything to do with houses or building them.

But amazingly,other people could post company names,and be allowed to do so.:rolleyes::eek::(

So I give up and wont name any companies here anymore.:(

whizbang

didnt have enough 3/4" insulation for the bigger pipes. So mainly the 1/2" ones are done

now there is little/no heat from the house keeping the pipes from freezing.
****** MUST insulate these ASAP!-******
Major amount of folks last year had insulation installed, but pipes were left outside the insulation. Guess what happened ?

oleras

paddy147 wrote: »

Not here,because I got lifted out of it and banned from the forum before,because a certain moderator took "personal issues" with me naming the company.
He rekoned that I must be working for them or have some link to them,when I clearly dont,as I work in IT and dont have anything to do with houses or building them.

But amazingly,other people could post company names,and be allowed to do so.:rolleyes::eek::(

So I give up and wont name any companies here anymore.:(

Have you PM'ed Neilw with the details ? Nothing against that.

hot to trot

OK. I didnt lay insulation under tank /pipes area. But will go and get 3/4 inch stuff and cosy them up . Thanks