New roof - frost problem in attic

Crafty424

I had a new roof put on my house last month which was done to building regulations standards including upgraded insulation. I have the building regulations paperwork and a 10 year insurance backed guarantee from the roofing company that did it. The problem is I was in my loft space last during the very cold snap last week and there was frost inside the roof all over the new membrane especially towards the eves. I spoke to my roofer and he said this was normal during cold weather. I was up there today to check and it’s still really frosty inside even though the temperature is a lot milder. So my question is this normal or do I have anything to worry about? Thanks for your input.

stuart45

Was the ventilation increased?

Crafty424

stuart45 said:

Was the ventilation increased?

According to my quote I would have a roof that:

‘incorporate eaves support trays with integral vents along with rafter roll vent over the wall-plates to enable a cross-flow of air above the insulation’.

Now I can see the rafter rolls above the eaves when I look into the loft but I have no idea if the vents have been put into the eaves. There are no vents in the existing soffits but my roofer said I wouldn’t need them with the above. When I put my head in the loft it feels cold and I can feel the air moving. I don’t know whether the insulation has been pushed too far into the eaves.

stuart45

The roof space will be cold, especially with the extra insulation. As long as there's enough ventilation there shouldn't be a major problem.
Frost is a bigger problem in really cold climates like parts of North America, where the frost is there for long periods, and the roof has OSB sheathing on top of the rafters which can rot. 
Short spells of frost on the membrane aren't such an issue.

Crafty424

stuart45 said:

The roof space will be cold, especially with the extra insulation. As long as there's enough ventilation there shouldn't be a major problem.
Frost is a bigger problem in really cold climates like parts of North America, where the frost is there for long periods, and the roof has OSB sheathing on top of the rafters which can rot. 
Short spells of frost on the membrane aren't such an issue.

Thanks Stuart. This is reassuring to hear. Yes, I’ve found lots of information online about frost inside roof spaces in the US and Canada (and ice damning) but nothing about UK houses having a problem with frost. The loft is much colder than it previously was and it’s been very cold here overnight the past week, Also the new roof tiles are thinner than the previous ones and I’ve been told the newer breathable roofing mebrane is more prone to freezing than the older ones. I’ll keep an eye on it in any case. The rest of the new membrane is as dry as a bone. 

Albermarle

The loft being colder maybe just means the insulation to the rest of the house is working better than before?

FreeBear

A cold loft space means that the insulation is doing its job. Frost would only be an issue if you have water pipes up there. If you do, check to make sure they are well insulated and perhaps consider trace heaters to prevent them freezing.

Crafty424

FreeBear said:

A cold loft space means that the insulation is doing its job. Frost would only be an issue if you have water pipes up there. If you do, check to make sure they are well insulated and perhaps consider trace heaters to prevent them freezing.

No water pipes up there. There frost is now condensation which looks quite concerning. I’m hoping it will naturally evaporate.

Swipe

Condensation is due to a lack of ventilation. I'd add some soffit vents.

Mistral001

I would check that there are no leakages of air from bathrooms or en-suites into the roof space. It only takes a small leak for moist air to enter the roof space and condense on cold surfaces there and freeze in cold weather.