I want to redo our loft insulation but not sure if it's too big a DIY job!

grumbler

fenwick458 said:

grumbler said:

5) ....... If you have low-voltage lights and transformers, I would take all transformers out and fix them to rafters.

I wouldn't do this, it would mean that whenever the transformers fail you have to go up into the loft and start digging around in the insulation, probably doubles the cost of replacing and the time taken rather than just pulling it out the hole from below

Going to a loft isn't a problem. People have boilers in lofts and service them every year. I replaced my transformer once in 20 years.

And I said "to rafters", meaning above the insulation. No need for digging and smaller/no risk of overheating.

a better solution would be to just fit 240V LED replacements, get rid of the transformers completely

Possibly, but low-voltage bulbs are more natural for LEDs and I expect from them to last longer than mains voltage ones. Cannot prove this with any statistical data though.

ashe

So having just posted on MisterNick's thread, I've just gone up into our loft and we have condensation everywhere on the roof felt, although it seems to be largely concentrated over our bedroom. There are no lap vents installed in the roof, and the only vent tiles we have are 2x roof tiles but these are used for extractor fans (the ducting for which I am confident is all on tight as I put it all on there yesterday) and secured with metal worm clamps, that ducting is all insulated as well. 

I've ordered 10x lap vents hoping that this will be enough, and in the mean time I have cut up some dense foam pipe lagging into 1-inch thick discs and put those between some of the strips of felt to give some air circulation points. 

Issue I have though is that the insulation feels a little damp to the touch, guessing it has been getting dripped on from the condensation. Is this still safe to lay over to prevent warm air getting up into the loft, or is it now "bad" and I need to start with fresh?

Will 10x lap vents be sufficient ventilation, or would I be better off getting a couple of roof vent tiles and just leaving them on as ventilation points?

Our soffits/fascias are complicated as they were apparently originally the exposed eave types e.g no soffits/fascias visible, just exposed eaves. My terminology is probably awful but basically looked like this:



At some point they got sick of maintaining that and UPVC soffits/fascia have been installed but over the wood; so there are no vents in this as I guess it would be a bit pointless - would we be better off putting some in anyways? 

grumbler

ashe said:

Issue I have though is that the insulation feels a little damp to the touch, guessing it has been getting dripped on from the condensation. Is this still safe to lay over to prevent warm air getting up into the loft, or is it now "bad" and I need to start with fresh?

You cannot prevent warm air getting into the loft by adding insulation.

Will 10x lap vents be sufficient ventilation, or would I be better off getting a couple of roof vent tiles and just leaving them on as ventilation points?

Impossible to say. IMO they don't chage much as there are gaps between the overlapping strips of felt anyway. And again, the more warm air is getting to the loft, the more ventilation you need.

Our soffits/fascias are complicated as they were apparently originally the exposed eave types e.g no soffits/fascias visible, just exposed eaves. At some point they got sick of maintaining that and UPVC soffits/fascia have been installed but over the wood; so there are no vents in this

Normally fascias must have some sort of vents, e.g.

ashe

grumbler said:

ashe said:

Issue I have though is that the insulation feels a little damp to the touch, guessing it has been getting dripped on from the condensation. Is this still safe to lay over to prevent warm air getting up into the loft, or is it now "bad" and I need to start with fresh?

You cannot prevent warm air getting into the loft by adding insulation.

Will 10x lap vents be sufficient ventilation, or would I be better off getting a couple of roof vent tiles and just leaving them on as ventilation points?

Impossible to say. IMO they don't chage much as there are gaps between the overlapping strips of felt anyway. And again, the more warm air is getting to the loft, the more ventilation you need.

Our soffits/fascias are complicated as they were apparently originally the exposed eave types e.g no soffits/fascias visible, just exposed eaves. At some point they got sick of maintaining that and UPVC soffits/fascia have been installed but over the wood; so there are no vents in this

Normally fascias mush have some sort of vents, e.g.

I think if they are installed from scratch they probably do but as ours have been "tacked on" they won't have that layer in that diagram. 

re: the lap vents, our felt is quite tightly fitted - I have, for now, forced in some squares of foam pipe lagging to hold them open but don't think really any airflow coming in between the gaps

bad wording on my part - not really warm air but I meant heat coming into the loft through the ceiling. Is the damp insulation now bad or will it dry out once covered if the condensation issue is remedied?

grumbler

It will dry, I wouldn't worry

Risteard

Very few LED downlights are insulation-coverable, and those that are carry a specific symbol to indicate this. Collingwood H2 Lites are about the only make and model I can think of which can be covered by insulation.

Chickereeeee

The soffits of my house have zero vents, and there are none in the roof itself. All the ventilation comes up the wall cavities, and the loft is very dry (and cold, in winter). Maybe OPs was similar, and somebody installed cavity wallm insulation?

ashe

Chickereeeee said:

The soffits of my house have zero vents, and there are none in the roof itself. All the ventilation comes up the wall cavities, and the loft is very dry (and cold, in winter). Maybe OPs was similar, and somebody installed cavity wallm insulation?

We definitely have no cavity wall insulation as we have drilled through for installing cables etc 

Grandad2b

Risteard said:

Very few LED downlights are insulation-coverable, and those that are carry a specific symbol to indicate this. Collingwood H2 Lites are about the only make and model I can think of which can be covered by insulation.

I could get worried by this... recently replaced 12V halogen downlights with new intumescent fittings and LEDs. Honestly cannot see the amount of heat lost from LEDs being a problem underneath mineral insulation.

ashe

My understanding is the main problem is when using 50w spots etc as they will get hot? Hue for example are 5w so MLM must generate far less heat?

if a hood is fitted then seems insulation is ok?