Felt lap ventilation

[fivegoldstars]

I'm having a problem with condensation in the loft - I've read all the stickies on this and other sites, and understand the causes/solutions.
I believe that inadequate ventilation is the problem in my case, and probably has been since the roof was installed some years ago. It is concrete tiles over roofing felt with a couple of ridge tiles, although I'm unable to find where they provide any ventilation. I had some plastic trays inserted on one side of the house when I had a little remedial work done, but even there, I cant feel anything in the way of a draught. Ideally, I'd have a couple of airbricks put in the gable, but it's over three storeys, access is on a neighbours land and the exterior is pebbledashed in a way that I'd like to leave undisturbed!
Having looked for other ventilation solutions, I've happened upon felt lap vents. For a test, I've used some strips of foam pipe insulation to open the laps, but the cobwebs in the loft are still still. The felt seems to be very taut, and overlapped by some margin - does anybody have experience of this kind of ventilation, or any pointers?

 

[Burnerman]

Seriously, I think you need to consider soffit ventilation here, and ensure that any insulation is covering the ceilings, and not falling into the soffit void.
Nothing the matter with your roof construction here.....or need for vented ridge tiles either.
John

 

[fivegoldstars]

Unfortunately, I don't have soffits. The fascia boards seem to be attached to the last course of bricks, with the roof trusses ending on the wall and just a slight overhang of tile. Ive seen fascia vent strips, but I'm not sure how easy these would be to retrofit.

 

[freddiemercurystwin]

Are you planning on DIY or getting a roofer in? A couple (depending on the length of the roof) of tile vents down low on each side may do the job.

 

[fivegoldstars]

Really hoping to do it DIY - there's always a million and one things wants doing, so anything I can do myself is a bonus.

 

[fivegoldstars]

Just an update.
May be coincidence - change in weather or some other factor - but since the laps were opened, the loft has dried out over the course of about a week. Will obviously keep my eye on it, but for now, this solution appears to have worked.

 

[shaun87]

How is your loft, is it still dry? I'm in the exact same situation as you were.

 

[fivegoldstars]

Yes, seems fine cheers.
Also, despite the strong winds, my roof hasn't flown off.

 

[declan1975]

Hello. not sure if you have sorted your problem but I had exactly the same issue. I inserted Felt Lap Vents in my felt and it cured the problem. I purchased them online they was not very expensive. I cant post the website on here but can I?