Condensation in loft

[azhali09]

Hi there,
We recently moved into 20 year old house and couple of weeks ago i went into the loft and there was a lot of condensation. I got three roofers to come and have a look and all of them identified the problem being no or very little ventilation. They suggested to have four roof vent tiles ( 2 at front and 2 at the back).

First guy said roof does not have breathable felt and he would need to cut the felt so air can flow. He said tile cost is £60 each and £110 for labour. So total £350.

Second and third guy said £25 for the vent tiles and £100 to do it.
He said he will cut the felt if I WANT HIM to do so and the reason for that was he said there is a gap between tiles and felt and air can flow in so there is no need to cut the felt. What concerns me with that is if felt is not breathable then without cutting the felt air wont flow in the attic. Am i right to think that?

Also difference in price quoted for the tiles is quite significant. The roof has Roman round tiles.

This is my first house and i have very little knowledge about these things. So any guidance would be really helpful.

Thx in advance

 

[b13kal]

Hi

Welcome to house issue .

What's happening is the hot air from your house is been lost into your very cold roof.

What you should do is make sure yours loft is insulated. Even the loft hatch. Then no heat will rise and no need for vent holes.

Loft insulation should dubble it's self , any small places will let heat from your bedrooms into the loft .

Do you get like a rain effect on the felt?

 

[azhali09]

Hi

Welcome to house issue .

What's happening is the hot air from your house is been lost into your very cold roof.

What you should do is make sure yours loft is insulated. Even the loft hatch. Then no heat will rise and no need for vent holes.

Loft insulation should dubble it's self , any small places will let heat from your bedrooms into the loft .

Do you get like a rain effect on the felt?

Thx for the reply.
I forgot to mention that loft is already insulated. There is half of it which has floor boards and i dont think that section is insulated. I do use that area for storage.
I think due to the nature of the loft and water tank etc it would be very difficult to fully insulate it. So heat will go up but i wanted to know what other board memebers think about solution and price which have been suggested by roofers. It does seems like a common problem.

 

[Roofer]

What you should do is make sure yours loft is insulated. Even the loft hatch. Then no heat will rise and no need for vent holes.

Unfortunately the insulation does not stop water vapour from getting into the loft so therefore ventilation is required

Vent tiles come from lots of manufacturers at different prices but these are readily available

http://www.roofingsuperstore.co.uk/product/harcon-in-line-redland-double-roman-tile-vent-grey.html

A labour price of £110 - 120 is (IMO) reasonable but the roofers are probably taking into account the mark-up on the vents as well

 

[noseall]

What's happening is the hot air from your house is been lost into your very cold roof.

Substitute "hot air" for "water vapour" which can migrate past permeable products such as fibreglass insulation (as stated by Roofer).

 

[azhali09]

Unfortunately the insulation does not stop water vapour from getting into the loft so therefore ventilation is required

Vent tiles come from lots of manufacturers at different prices but these are readily available

http://www.roofingsuperstore.co.uk/product/harcon-in-line-redland-double-roman-tile-vent-grey.html

A labour price of £110 - 120 is (IMO) reasonable but the roofers are probably taking into account the mark-up on the vents as well

What about one of them saying felt needs to cut and other one saying its not?

 

[Alastairreid]

The felt has to be cut.

 

[Tipper]

Interesting subject.

My roof was renovated a couple of years ago with the tiles stripped, some timber repairs carried out and then breathable felt, new battens and tiles replaced.

When up there last week I noticed condensation on the underside of the breathable felt near the ridge. It was a very cold but still day so I assume when windier it would go. The loft has over 200mm of insulation fitted so should be clear of condensation.

Is there anything I should do about this?

 

[noseall]

The loft has over 200mm of insulation fitted so should be clear of condensation

If you read the above posts, quilt insulation does not prevent the migration of water vapour.

Breathable membrane is not, on its own, a panacea for condensation related issues.

 

[seals]

Hi, I am getting the same issue, had walls and loft done last year and been up this week and the felt was soaking, I have vents in the PVC but I can't see them with the lights off so they might be blocked, but I have loft ladders and the hatch has no insulation on it,

was going to add some to the edges of it but was hoping someone could tell me best way to stick it on the latch.

also thinking of getting a air block fitted.

 

[Alastairreid]

Cut the insulation to the size of the hatch and staple polythene over it fixed around the perimeter.

Soffit vents need to be clear of insulation to function, you also need high level ventilation at ridge or as close as possible.

 

[seals]

I can as the ladders are attached to the hatch, so that where I am strugging