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Insulation

Condensation forming in loft only on one under side of the apex roof

Anonymous user 28/02/2024 - 4.06 PM

Hi Everyone Can anyone offer any advice, In very cold weather I have condensation forming in my loft, all the way along one under side of the apex roof (side not facing the sun). I have received a quote for the following work to resolve the issue. 1, Increase loft insulation from 100mm to 300mm 2, Improve airflow by installing a couple of new vents 3, Sort out the insulation in the eaves (on same side of roof) which is restricting airflow 4, Remove a centre platform that is no longer needed (a combi boiler was fitted in summer of 2021 and cold water tank removed from the loft) and add boards instead. 5, Raise all existing boards by an additional 200mm (for extra insulation) and re-board everywhere with new wood. 1, Is this a reasonable amount of work required to resolve the issue? 2, How much of a factor is the sun in preventing condensation on the other side of the apex roof or would other issues need to be present on that side of the loft in order for condensation to appear there as well? My next door neighbour with house built at the same time, with same layout and similar loft setup does not have any issues, although he does have a cold water tank and he fitted the boards himself. Due to lack of finances I want to see if I can resolve this myself first by buying felt lap vents to improve airflow, and laying as many of the following recycled plastic insulation roles as needed on top of the existing boards/platform to increase insulation. Recycled plastic insulation https://www.diy.com/departments/diall-insulation-roll-l-6m-w-0-37m-t-100mm/3663602481812_BQ.prd Can anyone offer any advice on what might be causing this to only be on one side of the loft and my current plan to resolve? Thanks

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2 Answers

Evergreen Insulation Services Limited

Rating: 5 out of 5

Norwich

Hmmm.... Difficult to say without seeing the architectural design of the property, and any existing ventilation measures in place. It does seem like your quote is an attempt to maximise the amount of work necessary, but it also may be just as an holistic approach. Nothing wrong with that. For most problems, there are often unexpected extra costs to the customer from any decent company, who actually have any integrity. I'd always advise using a professional company, and not be conned into using inferior products aimed at the DIY market! Personally, I'm forever rectifying over enthusiastic DIYer's work after they've been mislead by their own internet research. Most info on the web is there with an ulterior motive!!! Sell sell sell!!! If rectifying the condensation issue is your prime and only concern, then installing additional ventilation measures is all you need to resolve the problem. Be warned, felt lap vents only work adequately with certain tile types. No use installing them if you have plain tiles or slates for instance, as there is very little free airflow available. There are so many ways of ventilating a roof space adequately, but the best solution depends very much on each individual property and it's design and fabric. As already suggested, it seems to me like the company who issued the quotation are simply offering you a complete solution to ventilation, insulation and storage requirements. Lifestyle, and other 'finer' details, are always very big factors, and the difference, in similar properties, whereby some experience problems and others do not.

Answered22 January 2023

P J McCann

No reviews yet

Canterbury

If one of the tasks on the list is to remove insulation from the eaves as it is restricting airflow, I would consider doing this yourself first so that you can increase it. A lot of the time, people feel the need to butt their insulation right into the tight edges of the roof space. This in turn restricts airflow coming in at the eaves and form condensation at cold spots (the side that is always in the shade). Give at least a 50mm gap from the top edge of the insulation roll to the membrane of the roof. If you feel any cool air coming up, that’s a good sign. I’m not very knowledgeable on recycled plastic insulation but I would recommend rock wool as this is denser, offers a higher rating, is non itchy, you can cut it or tear it no problem and is fire resistant. After freeing the insulation at the edges of your roof space, give it a week or two and check if it’s made a noticeable difference. If it has, problem solved. If you’re on a budget and can’t afford to replace the insulation you already have, you can top it up in the meantime with insulation to suit your budget by laying it on top across your joists as I presume what you currently have runs between? The rest can be sorted at a later date, should you wish to.

Answered8 February 2023