Mr.

[BML]

I'm an 85 year old retired HR Manager who would like to do his bit for the environment by improving the insulation of the bungalow my wife and I live in. I put down insulation in the loft some 20 years ago and then put down flooring on top of it. We had a firm in to check the loft and they stated that we needed an extra 100 mm of insulation which required the flooring to be lifted, insulation put down and remedial work carried out on the flooring.

I wondered if the same level of insulation could be achieved by fitting some sort of fibre based insulation panels in-between the roof rafters.

[Conor]

Morning. Welcome.

 

With lofts it's best to stick to mineral wool type insualtion. Anything solid between the rafters risks condensation issues. How much in total is there in the loft? I'm guessing 100mm between rafters? You really want 300-400mm in total. If you end up lifting the flooring, may as well put as much as you can Inna's the insulation itself is relatively cheap (compared to the cost of lifting and raising the flooring).

 

Or.... Do you use/need the flooring in the loft? You could simply lay more mineral wool on top...

 

[Ian]

7 hours ago, BML said:

I'm an 85 year old retired HR Manager who would like to do his bit for the environment by improving the insulation of the bungalow my wife and I live in. I put down insulation in the loft some 20 years ago and then put down flooring on top of it. We had a firm in to check the loft and they stated that we needed an extra 100 mm of insulation which required the flooring to be lifted, insulation put down and remedial work carried out on the flooring.

 

I wondered if the same level of insulation could be achieved by fitting some sort of fibre based insulation panels in-between the roof rafters.

 

As @Conor says the main issue is that all the loft insulation needs to be in the same place and, with your roof, it would be best to add it to the insulation that you’ve already got across the floor of the loft.

Adding extra insulation to loft spaces can sometimes lead to condensation problems in the roof void - the degree of risk depends on how well ventilated your loft space is and the type (if any) of the roofing felt that’s under the tiles.

Edited December 8, 2021 by Ian

[Olf]

Is the flooring actively used? If not, then there is no need to lift it, just add insulation on top. If yes, then rigid insulation boards (creating floating floor) may be the answer.

I'm doing a hybrid: in the middle (under the ridge) rigid insulation boards covered with planks to spread the load, but away from the centre standard wool, proportionally thicker. That way I loose less headroom where access is needed, and save on cutting the rigid boards (nasty dusty affair)

[Caddy]

3 hours ago, Olf said:

Is the flooring actively used? If not, then there is no need to lift it, just add insulation on top. If yes, then rigid insulation boards (creating floating floor) may be the answer.

I'm doing a hybrid: in the middle (under the ridge) rigid insulation boards covered with planks to spread the load, but away from the centre standard wool, proportionally thicker. That way I loose less headroom where access is needed, and save on cutting the rigid boards (nasty dusty affair)

I've done pretty much the same. 100mm PIR in a strip down the middle where I have flooring and 100mm+170mm loft insulation towards the eves where I don't need the height. Seemed the best comprimise to me at the time.

[BML]

Many thanks for your answers. There are so many advertisments covering this area and the one I saw promoting a spray on material inbetween the rafters sent shivers down my back because even a non profesonal as I am wonderd about blocking out ventalation.

The problem with our loft floor is the same as many dwellings abandoned by the children who left loads of stuff up there so the flooring is actively used and I'm loath to spend money on raising the floor.

[Olf]

16 hours ago, BML said:

loads of stuff up there so the flooring is actively used

That's not active use - the stuff will be as happy on top of rigid boards as if it was directly on the floor. Walkways would be active use, a layer on top to spread the load and protect the insulation boards would be a good idea, even a sheet of OSB or plywood will be more than enough.

The only challenge is at the eaves: with rigid boards that means messy cutting to follow the roof slope (though it can be done outside, if taking advantage of wind direction it may be a non-issue), remembering to leave some gap for ventilation. Also rigid boards will be pricier than wool, but will end up cheaper solution when considering lifting the floor, and they will also save some headroom (100mm PIR gives the same effect 200mm wool). Added bonus is reduced draughts (especially if all the joins treated with aluminium tape) and reflective surface reducing heat absorption on sunny days (and to lesser extend wasting heat escaping the house in Winter).

Depending on where you live,  there may be plenty of offcuts available locally (via ebay/gumtree/facebook etc) and it can be done on budget - that's how I got my pieces, both parties were happy as I had them for pennies, the guy saved on a skip.

[BML]

What about using block foam cut to size to fit in between the joists? By the way, the replies notification dosent seem to work.

[Iceverge]

Hello @BML and welcome. 

 

A couple of questions. 

 

1.Do you have any sketch or picture of the loft as it is at the moment?

 

2.Does the flooring cover the entire surface or just an area in the middle?

 

3.Is there lots of structural timbers everywhere or is it a proper attic space?