Any areas not to insulate in loft?

[wbcdtrparis1209]

I am intending to top up the 100mm glass fibre insulation to 300mm in my house built in 1992. I note however that above the stairwell the original builders have not put any insulation in that area. Would anyone know of any reason for this ?

 

[freddiemercurystwin]

They were lazy!

PS make sure you keep a gap at the eaves to allow for ventilation.

 

[DIYWell]

I'd agree - lazy builders.

Insulate the entire surface, there shouldn't be missing areas, nor should there be any gaps to allow air to convect through.

At the eves, don't stuff the insulation in tight. If you do, put in eve vent trays to allow air to come up through the eves into the roof void. There's also a school of thought that says you leave about 250 mm at the eves at 100mm depth and top up the rest. (I think I saw that in a technical paper on the Kingspan website).

you might want to post in the sparks forum, but be careful of putting insulation over cables. Lighting cables you're probably ok with, but heavier cables like for a shower you don't want to cover up. When current passes, cables heat up, the more current, the greater the heat increase and this has to go somewhere. If it stays cossie in the insulation there's a risk of overheating or fire.

Also, once you've done the job, take a look up there every 3 months or so. There shouldn't be any condensation. If there is, you need to look at the ventilation again and make sure enough air is trickling through to keep things dry.

 

[big-all]

I'd agree - lazy builders.

Insulate the entire surface, there shouldn't be missing areas, nor should there be any gaps to allow air to convect through.

At the eves, don't stuff the insulation in tight. If you do, put in eve vent trays to allow air to come up through the eves into the roof void. There's also a school of thought that says you leave about 250 mm at the eves at 100mm depth and top up the rest. (I think I saw that in a technical paper on the Kingspan website).

you might want to post in the sparks forum, but be careful of putting insulation over cables. Lighting cables you're probably ok with, but heavier cables like for a shower you don't want to cover up. When current passes, cables heat up, the more current, the greater the heat increase and this has to go somewhere. If it stays cossie in the insulation there's a risk of overheating or fire.

Also, once you've done the job, take a look up there every 3 months or so. There shouldn't be any condensation. If there is, you need to look at the ventilation again and make sure enough air is trickling through to keep things dry.

you must have airflow through the loft
in reality if you dont feel airflow on a windy day you are lacking airflow

but the real test is when you open the loft hatch there should be no condensation
then if some appears whilst your in the loft it should be gone idealy by 2 days later [or maybe sooner]but definatly within the week

 

[wbcdtrparis1209]

Thanks for all your prompt responses. Will take note of potential condensation problems but think it should be OK as the eaves all along their lengths have air vents. Electrical cabling is lighting circuits only do they need to be lifted?

 

[DIYerHELP]

Do not insulate under the water tank if you have one in the loft

 

[DIYWell]

Thanks for all your prompt responses. Will take note of potential condensation problems but think it should be OK as the eaves all along their lengths have air vents. Electrical cabling is lighting circuits only do they need to be lifted?

Purists would say that the wires run over the insulation, but I've never seen it done by firms who fit top-up loft insulation. Also, I doubt there would be enough slack.

If you're not running lots of incandecent bulbs at the same time, you'll be safe enough since there will be very little current drawn so not much heat to dissipate. If you want, check the wiring and make sure it is clipped to the woodwork.

If in doubt, speak to a qualified electrician.