Pack 20 Roofing Felt Lap Vent Stops Loft roof Condensation/Attic Space Ventilation Airflow

Hadn't been in the loft for a couple of months so was really surprised at my findings when I did go up a couple of weeks ago. The ceiling was totalky drenched with water droplets (condensation), there was damp on the floor, insulation and rafters. A couple of rafters were showing signs of mold growth, everything felt damp and some boxes actually had puddles of water on them (no exaggeration). Immediately did some research and ordered these items. Cleaned out mold fully, tidied up loft and installed these about two weeks ago, and despite having lots of reservations, these things worked a treat. Loft is now completely free from any condensation ... even signs of the mold had disappeared, so genuinely surprised and could not believe it. Installation was very simple. The loft is now obviously colder due to the outside air coming in, but better this than condensation. Early days but time will tell if it does deliver long term. Main downside is price which seems very expensive for what is essentially very basic flimsy PVC. I guess you're paying for the design, ease of use and primarily the niche product/market.

Fantastic! We recently moved into our first own home, an early 1970's semi-detached house with practically no loft insulation. I fitted a 12 inches deep layer of insulation to the loft and it certainly helped the warmth in the house but on the first venture into the loft on a frosty day I found the whole place was like it was raining indoors with condensation dripping off the inside of the roof felt, especially bad on the colder front of the house which gets less sun. With mounting repair bills for the old house we were really worried about how we could fix the problem as everything in the loft was soaked and damp was destroying anything we had stored up there. Searching for a solution I learned about these felt lap vents from a roof repair specialist who post videos on youtube and advised these may be a good DIY fix. A quick search on Amazon and I was delighted to find some for sale so I bought a pack of 20 in the hope they would help the problem. The vents are very easy to fit and I installed 10 per side, 5 low and 5 high, staggering the vents so no two are in line. Anywhere the felt was a bit stuck I used an old butter knife to gently free it up so the vent could slide in. Immediately you can feel a slight air current entering through the vent and with all 20 vents fitted I towel dried as much of the damp belongings as I could and left it be for a couple of days. Upon checking the loft again a couple of days later I found the loft was dry, no condensation and the damp musty air was gone. The vents have been in place for a few weeks now through frost, snow and heavy rain and our loft is dry and our belongings have been saved. We were so worried about possible high repair bills and now are delighted the problem has been solved so easily and cheaply. I would highly recommend these vents for anyone suffering from a damp attic caused by condensation.

We live in a 4 bed detached house and suddenly started having trouble with condensation in the loft - it was pretty bad with drips coming off the felt. Rather than mucking about with getting soffit vents fitted I thought I’d give these a whirl. I read other reviews that said that you’d probably need more than 10 so I thought I’d start with 20 and see how it went. I tried shoving them in randomly between the overlaps in the roofing felt and often found that either tiles or wood batons were obstructing the vent from being fitted. The result was that the placement wasn’t quite as random as I’d have hoped (which is said to improve air flow). However, the end result is good. We don’t seem to have any evidence of condensation any more! That said, it has been a bit warmer these last few weeks so only time will tell. A little expensive for what they are (considering they’re just injection moulded plastic) and one of them broke a little during insertion. Others have said that sticking some halved pipe insulation between the felt would work just as well but these were convenient and pretty easy to install - aside from the issues I had with the exact structure of my roof.

I have had issues with very bad condensation in the loft for a couple years now, I’ve had roofers quote me in excess of £1k to fix (roof vents etc), additionally, my loft is partially boarded which supposedly alters the airflow. I saw these mentioned on a forum and thought it was worth a go. Delivered quickly and they are pretty straight forward to fit. The instructions say you should try to get most of them as close to the eves as possible, also under the batons if possible to maximise airflow. I decided on ordering 20, one between each beam on both sides, with every other being as low as possible. Then staggering the ones at different heights in-between. I could notice the difference in airflow almost immediately and this pretty much cured the condensation in most of the attic, but highlighted that the seal on my hatch has failed. This is because some condensation remained, but only directly above the hatch, nowhere else. After replacing that seal my attic is now completely dry, even during this recent cold snap, where before it would’ve been absolutely soaking up there. I can without a doubt say that these do as advertised and increase the airflow in your loft, but there may be other underlying issues that may also need to be addressed in order to fully cure any condensation. Overall I am very happy I have managed to solve this condensation issue for a fraction of what I was quoted by professionals.

Somewhat skeptical at first as to whether or not these would actually work. I was getting a lot of condensation forming on underside of the felt, probably due to some of the real cold weather we have been having. However in a few days, the loft has completely dried out and there is no sign of anymore condensation. Chose Manthorpe as I had earlier installed a Manthorpe Loft Hatch which was excellent. Vents are very easy to install, although climbing across ceiling joists to install them at a low level was sometimes precarious. I installed vents between every other joist on both sided of the roof. Great job. I feel they are somewhat pricey for a bit of plastic, but they are the only ones I have found and they do the job they are design for, therefore I guess they are worth the money.

Went into loft recently for first time in a while, and actually thought it was raining inside, since there was so much condensation dripping off the felt! After a panicky Google search, I noticed there was a lot of people recommending lap vents for condensation issues. I was sceptical but decided to buy these and give them a try. A few days later, I couldn't actually find any condensation drops at all on the felt! They seem like such a simple device, it's easy to think that they won't actually do anything, but they definitely have in my case. In terms of fitting, they are very easy to attach. From the advice I read, it is best to fit them as close to the eaves felt flaps as possible. It was a little bit awkward for me to access those since I have loft boarding, but after crawling on my belly a bit, I was able to fit a row of them in the bottom row of flaps. Each one should only take less than 30 seconds to attach. Overall, very happy I have managed to solve this condensation issue for less than £50.

Noticed drips on loft boarding, which came from the apex of the roof, where the ridge and rafters in small areas were damp. This appears to have happened when the insulation thickness was increased and flooring placed on plastic feet over ceiling joists. These plastic vents slide where there is a horizontal lap in the roofing felt. Be careful if you have the older type felt, it becomes stiff and brittle with age. As long as the vent tucks in enough to hold it in place you should feel air coming in, which is the purpose. I got 20 but only used about 6 or 7 as there weren’t many places I could insert them, but it worked, no more signs of damp areas on the timbers.

My house has suffered for several years with a condensation problem in the loft, due to bituminous felt and inadequate ventilation as built. I have used condensation absorbers with limited results, and the price of these has crept steadily upwards in recent years. For under £50, the kit of 20 of these vents seemed worth trying. I installed them in February when we were going through a few cold snaps, and within a couple of weeks the slightly musty smell had gone, never to return, and the dripping of condensation on the loft timbers and flooring has completely disappeared. OK, so the loft is a bit colder, but I don't live up there, and it might be a bit cooler in the summer. I can thoroughly recommend these lap vents to anyone experiencing similar problems. They are a doddle to fit, but to get the best through-flow of ventilation, some need to be installed at low level over the eaves, and for a guy in his late-60s that was a bit of an ask, but well worth the effort. Excellent product.