Loft ventilation question

[chatlow]

Sorry, I know there are many threads on this, especially this time of year.

We recently boarded the centre section of our attic using loft legs and added a further 170mm of insulation to the existing 100mm between the joists. I made sure to leave a gap around the edges.

Up there yesterday and lots of condensation Drips on the boarding and boxes. Cleaned up some of it.

Have since realized that the previous owner had new uPVC soffits fitted before selling and there are no vents on them. Suspect they have fit these over the existing. I am really struggling to get a full view of the soffit via the loft, but my plan was to cut a few holes into the soffits from below - check to see if the loft is visible - then fit disc vents. This will likely be done from bedroom and bathroom windows, unless I can get a good ladder next weekend. Plan on 2 at the front and 2 at the rear of the house.

I'm also going to get a pack of 10 felt vents and fit these.

Hoping this will help the situation but would welcome any thoughts on it

Thanks

 

[RandomGrinch]

I am really struggling to get a full view of the soffit via the loft, but my plan was to cut a few holes into the soffits from below - check to see if the loft is visible

Take a little caution, if you have an older house, uPVC soffit boards were used as a coverall for many things, including rotten wood and asbestos soffit boards.
If you can investigate from the loft first, you can be sure you're not drilling into something you shouldn't be.

Apart from that, your plan sounds like a good start (I would probably go for a few more soffit vents). It's also worth checking for other sources of moist air moving into the loft, such as unsealed spotlights in the ceilings, or a poor seal around the loft hatch.

 

[chatlow]

thanks - appreciate the reply - will take note of that. Out of curiosity, are felt vents more likely to help more than soffit vents or is there a need for both? Should have mentioned that the house is 1996 but no signs of Asbestos. Surprised there hasn't been issues in the past with damp etc because the previous owner only had the 100mm insulation in there

 

[RandomGrinch]

appreciate the reply - will take note of that. Out of curiosity, are felt vents more likely to help more than soffit vents or is there a need for both?

Felt lap vents are a straightforward DIY solution, but it only provides a limited amount of ventilation from the draft that comes through the slates/tiles, hence the need for many of them.
Soffit vents can have a larger open cross sectional area (i.e. from continuous vents), but the cross ventilation better benefits the lower portion of the roof.
Many new-builds will now have continuous or over soffit vents, plus a ventilated dry ridge system.
So there is possibly a case for both, if there are condensation problems.

 

[chatlow]

thanks, will fit 20 felt vents first, see how it looks after a cold snap, then try fitting some soffit vents if the problem persists

 

[chatlow]

Just wondering if there are any solutions to quickly remove the current condensation that's there? I need to wait until Weds to fit the vents, but even then Im wondering if the extra air flow will be enough to clear up what's already formed up there..

 

[amfisted]

Just wondering if there are any solutions to quickly remove the current condensation that's there? I need to wait until Weds to fit the vents, but even then Im wondering if the extra air flow will be enough to clear up what's already formed up there..

I've answered your post on the " fitting soffit vents" thread, but regarding removing existing condensation, if the loft is completely sealed you could use a dehumidifier up there if you have one. If you don't have a dehumidifier then you'd have to pay upwards of £150 to buy one big enough to dry out an entire loft, so probably not worth the cost unless you're really keen to start with the blank canvas of a dry loft.

I'm a big fan of dehumidifiers: we had a significant winter problem with condensation just after moving into this bungalow, so much so that one of the bedrooms refused to dry out sufficiently to allow me to hang wallpaper. I bought a dehumidifier and within a couple of weeks with regular use, all the condensation had gone.

 

[chatlow]

thanks and yes just seen that reply - will message now. Yeah it's completely sealed. No dehumidifier unfortunately, I'll ask around to see if anyone has one. Suppose I'm wondering (hoping) whether the felt vents (fitting 20) will be enough to remove the existing moisture (we live in a relatively rural and exposed area)

 

[chatlow]

I'm also wondering if all the work I did 2 months ago in the loft (boarding and insulation) has actually caused this. Mostly because the loft hatch was left permanently open for a few days whilst i did this - but overall temps were higher then - but I would have been breathing a lot up there too.