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Ricko

Condensation in roof space.

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Hi, a quick question on behalf of my lady friend. She's just been up into her attic to retrieve her Xmas decorations and has told me that there seems to be a lot of moisture up there.

The roof is tiled and in good order.

I explained that it's most likely condensation due to the cold weather outside and the heating being on inside the house.

What's the answer to prevent it? Roof vents?

Thanks in anticipation.

Edited by Ricko

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12 minutes ago, vampire said:

ventilation 

This....

Get air in!!

4 minutes ago, team tractor said:

Make sure the insulation isn’t pushed right in to the corners . We’ve seen idiots filling up the vents

This.....insulation companies....agrhhhhh!

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If you have any water tanks, check they are not warm/hot .

If so you have heating fault.

HTH

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Where is the moisture coming from would be my worry and to look for. If no ventilation there is no air to circulate so shouldn't be that wet and damp.

Either warm air from the house is getting up there and condensing or there is some other source of moisture. If it's leaking warm air from the house to attic loft space that needs sorting as your loosing heat.

A couple of soffit vents on opposite sides of the house should sort out enough ventilation, don't want too much.

One house I had was fitted with grill vented soffit boards, in moderate winds the heat was sucked out the house. In high winds the loft hatch used to get blown down. 

 

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7 hours ago, Ultrastu said:

Or use modern  roofing felt that breaths .

But that is a re-roofing job.

I assume that if your friend has been regularly storing things in the roof that this condensation is a new thing.

Check to see if the eaves ventilation has been reduced by fascia and soffit boards being clad with upvc. If it has been done recently get the company to come back to put more ventilation into the soffit boards and make sure the roof space has ventilation sleeves to ensure that the air can get up into the roof space from the eaves and blow through.

As has been said before check that the insulation hasn’t been taken down into the eaves to block the airflow within the roof. You can get plastic sleeves which fit between the rafters over the top of the insulation to maintain an air gap above the insulation and this means the insulation can cover the ceiling right out to the walls so that you don’t get cold spots at the in the corners of the rooms which can lead to condensation and mould growth around the edges of the bedroom and bathroom ceilings.

You need plenty of ventilation up above the roof space insulation if the insulation has been upgraded, from that which previously existed when the house was built, because the roof space would have been relatively warm with the heat escaping from below, when the house was built. With upgraded roof space insulation the source of heat from the living accommodation has been cut off and the roof space is now much cooler hence the condensation.

 
 

PM me if you need further advice.

Edited by Fisheruk

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Another thing to check, if she has a combi boiler vented through the roof, check the flue. It may not be secured correctly and started to leak inside the roof space! 

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Age of the property? Roofing felts of bitumen/plastic variety sweat badly ( remember that Geoff Capes advert where he is sitting on a piece of felt or something like that) 

Replacement is the ideal, but failing that then plenty of soffit ventilation, dry ridge system and create a secondary vapour barrier using a multi layer foil or something- this creates a vented void and helps.

Reroofing with a breathable felt is the ideal solution, but expensive.

 

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After years of trying to sort mine out the only thing that stopped it was replacing the sarking felt.

I fitted sottit vents all round, put large air vents in the gables for a through draght, made sure the insulation was well back from the edges, fitted plastic vents between the sarking joints to improve air flow. Considered fitting a fan to move the air around and possibly venting the ridge tiles.

My house has very little head room, infact I can only just kneel up in the centre and what happens in winter is the frost forms inside on the felt and melts during the day. If its not windy then its shower time.

My working solution was to cut the old felt out leaving about 2" on each side of the roof timbers about two 3rds down and screw some 1/2" batterns to the sides with roofing membrane between them. Not a prety job but it worked.

cGjcaZs.jpg

O9mC0yQ.jpg

dV2hNvc.jpg

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57 minutes ago, bear-uk said:

After years of trying to sort mine out the only thing that stopped it was replacing the sarking felt.

I fitted sottit vents all round, put large air vents in the gables for a through draght, made sure the insulation was well back from the edges, fitted plastic vents between the sarking joints to improve air flow. Considered fitting a fan to move the air around and possibly venting the ridge tiles.

My house has very little head room, infact I can only just kneel up in the centre and what happens in winter is the frost forms inside on the felt and melts during the day. If its not windy then its shower time.

My working solution was to cut the old felt out leaving about 2" on each side of the roof timbers about two 3rds down and screw some 1/2" batterns to the sides with roofing membrane between them. Not a prety job but it worked.

cGjcaZs.jpg

O9mC0yQ.jpg

dV2hNvc.jpg

Yes, you have done the correct thing to improve the roof space ventilation. The original sparking is the old BB747 type 1f. Non-breathable, which was fine when the house was built but with increased roof space insulation extra ventilation is required.

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Its been dry now for 3 years so definatley working. I could go down another meter but it gets harder to fit. The side batterns are the strips of wood that are fitted between the long lenghts at the woodyard for airflow. And free as normally scrap.

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On 02/12/2019 at 23:26, Shufti said:

If you have any water tanks, check they are not warm/hot .

If so you have heating fault.

HTH

This is first thing to check 

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