How to retrofit insulation air gap?

johney · 27-11-2016 08:22PM #1

Hello folks,

I bought a renovated bungalow a while back. The attic had just been spray foamed by previous owner. On very warm summer days the insulation would weep and drops of water would appear. After investigation I have found that there is a card about 1 inch from the felt so leaving a 1 inch air gap between foam and felt. However, as the house is a very old bungalow type, there is no soffit, just a pvc facia nailed to the wooden facia board, which is flush with the external wall. The facia is pushed up very tight against the slates with no air gap. In short, there is no air getting in anywhere. How to remedy this? Was thinking of boring a few holes through the fascia just under the slates, but this may allow water to enter. Anyone any ideas? Many thanks

BryanF · 27-11-2016 10:09PM

http://www.glidevale.com/fascia-ventilators/p/3

johney · 01-12-2016 08:43PM

thanks bryan.

looks good. Only the gutters are new and I don't really want to take them down.Any other solutions?

BryanF · 01-12-2016 10:23PM

Did you read the link? It goes over the fascia.

Calahonda52 · 02-12-2016 02:43PM

Two issues at play here:
1: venting the 1" space between the felt and the cardboard
I believe the glidevale product will address this, at least in part.
However it depends what has happened at the ridge board: there may be no continuous air path across from one side to the other so may be necessary to address this at ridge level.
2: venting the internal attic space.
Based on what is written, the weeping may be caused by what is called solar drive. Look it up.
The other question is what type of foam was used: open or closed cell. Look up again.

IMO, it is imperative, repeat, imperative to make sure the internal attic space is internally vented because if the foam is retaining moisture then there is a risk that the roof timbers will rot over time.

However, ventilating the attic space may negate the foam insulation so maybe you can tell us a bit more about the house construction, especially the roof: [hipped, gabled etc] as well as what other insulation in attic space etc. etc
Is there an open, uninsulated cold water storage tank in the attic, etc etc...
Is the attic access door airtight?
are there pipes from hot press going up into attic though a big hole in hot press ceiling?
etc

johney · 03-12-2016 10:48AM

lads,
yes bryan I read it.There are gutter brackets which implies the gutters must be re positioned. At any rate, the gutter is well up against the slates so perhaps I have no other option but to remove them.
Calahonda, The house is a tee shape. Basically it was a straight little gabled bungalow like what you would see in 1940's TV, and the previous owners built a flat roof back kitchen at right angle to main house, sometime in the 80's. Owner after that built an upstairs room on the flat roof, tied the 2 roofs together, reroofing everything.This is when he spray foamed the whole house. Stairs installed between old and new building,and door to old attic which is open much of the time. The new upstairs room has plenty of soffit so I can install vents here. At any rate I cannot really see what's going on here as it's now a bedroom.The old attic space is the problem.
Open cell foam. Seen it full of moisture and dripping in the summer.
I believe you are right about ridge board. There is no continuous path for air.

Uninsulated water storage tank in attic and pipes going through hole into hotpress below, however, I did this and the issue was before this was even done.
The moisture seemed to be heaviest near the chimney but there should be no leaks there as I had it done. But could water travel from chimney up to 7 metres away through the foam?
I have the option to put a window in attic gable for occasional air circulation but the timber ventilation problem still exists. I did manage to speak with the contractor who installed the foam who said his foam is 80% breathable and as felt was new green breathable type, so there was no issue!!! Different in practice I have to say.
I will look up this solar drive you mentioned.
Many thanks lads for your interest and responses. Much appreciated.

Calahonda52 · 03-12-2016 08:45PM

johney wrote: »

lads,
yes bryan I read it.There are gutter brackets which implies the gutters must be re positioned. At any rate, the gutter is well up against the slates so perhaps I have no other option but to remove them.
Calahonda, The house is a tee shape. Basically it was a straight little gabled bungalow like what you would see in 1940's TV, and the previous owners built a flat roof back kitchen at right angle to main house, sometime in the 80's. Owner after that built an upstairs room on the flat roof, tied the 2 roofs together, reroofing everything.This is when he spray foamed the whole house. Stairs installed between old and new building,
and door to old attic which is open much of the time.
The new upstairs room has plenty of soffit so I can install vents here. At any rate I cannot really see what's going on here as it's now a bedroom.The old attic space is the problem.
Open cell foam. Seen it full of moisture and dripping in the summer.
I believe you are right about ridge board. There is no continuous path for air.

Uninsulated water storage tank in attic and pipes going through hole into hotpress below, however, I did this and the issue was before this was even done.
The moisture seemed to be heaviest near the chimney but there should be no leaks there as I had it done. But could water travel from chimney up to 7 metres away through the foam?
I have the option to put a window in attic gable for occasional air circulation but the timber ventilation problem still exists. I did manage to speak with the contractor who installed the foam who said his foam is 80% breathable and as felt was new green breathable type, so there was no issue!!! Different in practice I have to say.
I will look up this solar drive you mentioned.
Many thanks lads for your interest and responses. Much appreciated.

What exactly do you mean by the bolded text:

If the spray foamed attic space is open to receive moisture laden air from the rest of the house then therein lies the problem, or at least a lot of it.

If the green felt is breathable then the glidevale idea is not required, if I understand the problem correctly

BryanF · 03-12-2016 10:24PM

A Note to all foam advocates

Double battens above breathable membrane, will that cut it?

How to retrofit insulation air gap?

Comments