Felt Lap Vents in Loft

[SirGalahad]

Felt Lap Vent | Manthorpe

The Manthorpe Felt Lap Vent is a refurbishment product designed to increase the amount of ventilation into existing roof spaces. Usually fitted retrospectively to properties with additional loft insulation recently installed, however the Felt Lap Vent will help to combat the problem of...

www.manthorpebp.co.uk

So there is a build up of condensation in my loft. I bought some Manthorpe Felt Lap vents - looks like an easy fit. You just push them under the sarking but for some reason I cannot get them to fit all the way down -so they are sticking up about 2-3cm as they seem to be hitting something.

So is this ok or should I try force them in more? Also I couldnt see any daylight shining through so not sure if I have installed them properly.

 

[Nige F]

Sarking hell = don't force them . They'll be fine

 

[datarebal]

They are probably pushing against a batten .
You don't need to buy anything to open up laps , you can use anything . Sections of over flow , batten .etc overflow works good

 

[SirGalahad]

I live in a three bed terrace and I couldn't work out how many I needed. I bought ten so is that enough or do I need more.

I staggered them.

 

[datarebal]

See if it cures the problem .. if not open up a few more..
The effectiveness really depends on the roof covering ..example slate you would need a lot . Plain tiles (i think you may have these ) need a favor few too.
Pan tiles like a grovebury or similar need not so many .
Check your insulation , check your extractors are connected to outside , insulate loft hatch ..

It's that time of year

 

[amfisted]

Just done the same here.

1960s semi detached bungalow, moved here in May, condensation problems started last month with the first coldish day. I bought a dehumidifier which dealt very efficiently with the problem downstairs, but in the roof space the underside of the roof liner is wet and in places drops of water are visible. So I installed 10 soffit vents, half at the front, half at the back, and 10 felt lap vents across both slopes ( it's a cold roof). Just waiting now to see whether this makes any difference and if not I'm considering PIV. PIV of course is a whole house ventilation solution and we only need condensation in the roof space sorting, not bothered about air quality ( cough). Its also expensive, so hoping we don't need to go down that road.

I'd be interested to hear whether your lap vents work, Sir Galahad.

 

[TonyW2]

Is there any advantage to using these mouldings instead of just inserting something (wood strip, pipe insulation, plastic pipe, etc) to separate the felt layers?
Do they increase risk of insect access?

 

[datarebal]

Insects get in regardiess . Bit of overflow pipe work well . Look in a builders skip you might see some off cuts

 

[SirGalahad]

I don't think the lap vents are working they seem to hit a batten and I cannot see daylight so may need to open up the eaves - how do you do that on a 1920s terrace stone brick with slate roof.

 

[amfisted]

Its a particularly bad year for condensation in lofts, from what I can gather. An acquaintance of mine who is a surveyor tells me that his colleagues are coming across a significantly greater number of roof spaces which are badly affected by condensation than is usually the case at this time of year. It might be that many of us who are currently suffering the scourge of loft condensation are just going to have to manage/ ignore the problem till the weather warms up. Which doesn't mean, of course that we shouldn't do everything we can in the meantime to stop it coming back.

 

[GraPC]

Sorry to tag onto an existing post, but I wondered if there is any issues with the lap vents causing the tiles to lift up in the wind or driving rain getting in? The installation guides all seem to suggest that this is a possibility?

Has anyone had this issue or are they simply covering their backs in case it did happen?

I’ve got some installed along with some tile vents. I’m wondering if I even need the lap vents if they could cause damage.

Thanks

 

[datarebal]

Loose felt Laps can lift tiles in storms . Certainly on the coasts

 

[GraPC]

Loose felt Laps can lift tiles in storms . Certainly on the coasts

Ah right. So if the laps are tight with the vents fitted it shouldn’t be an issue?

 

[James South]

I'm no expert but I've seen so many places recommending these and so few posts anout issues etc. I can only presume they are ok. Plus with lots of reputable places selling them. I've added 5 to my loft and as the slip between the felt, which didn't need prized open, I can't see the damage they will cause. Time will tell though.

I'm guessing the manufacturer is just covering themselves.

 

[GraPC]

Yeah I think you’re right. I’ve not noticed any issues so far and we’ve had some windy/rainy days.