Loft boarding. Was expanding supposed to be used?

8 May 2023
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United Kingdom

New here.

I had a loft done by someone recommended to me who had their loft down also. Just boarding and kingspan used level with rafters with gap needed for ventilation.

He advised I get tile vents installed by a roofer but I thought the vent laps do the same thing? Also, I could feel a breeze prior to the kingspan installation.

My concern is the expanding foam used all around the perimeter. Is it best to remove that? I can’t find anything to say what is suitable for ventilating around the edges of the loft.


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It's the rafters that need ventilating, not the whole loft. As long as there's a gap between the top of the kingspan and the felt (and that gap is ventilated at the eaves and ideally at the ridge) you'll be fine
If you put kingspan between rafters in such a way that world air can vent around it and into the loft space, you might as well stand it up in the garden for what benefit it will bring to your heating bill
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If you only have eaves ventilation then where will all the moisture go in the winter when the warm air gets through the insulation and wants to condensate upwards of the eaves? Periodic checking through the colder/winter months is advisable.
The OP has had Kingspan fitted. Won't they help to bounce some of the heat away? At a minimum, wouldn't it/they reduce hot air entering the loft area?
I didn't fully understand what you were asking, opps, but yes the foil surface of the board will reflect some inbound radiant heat as long as it is not in conductive contact with a warmer material. If the slates are warmer than the loft space then the insulation will act to reduce the rate at which that heat flows into the loft space. The loft space stays cooler for longer in summer and warmer for longer in winter
Hi, thanks for the replies. I meant to say loft boarding done.
On reflection, I wish I got it plasterboarded instead since it didn’t make too much of a difference in the winter months.
I haven’t seen any condensate in the colder months since the temperature within seems to be much higher than outside and the humidity is always around 40-50%.
My question was relating to the use of expanding foam all along the perimeter but I have been assured by the person who did it that they didn’t block the eaves, more so the gap where kingspan touches loft boards.

I aim to install a velux window with a trickle vent to remedy the airflow issues

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