Loft insulation quotes in a 1907 house

[lizziecupcakes]

Hello
I have been getting a wide range of quotes for putting in 300 mm of insulation (knauf brand : link here).

The job entails lifting up the boarded loft and returning boards to us (we will keep them/dispose ourselves), remove old insulation (some yellow stuff, 100mm, but not sure the brand or when it was installed), then put down new insulation. The loft is about 55 sq metres in total.

£1299 for everything from one (but they keep messing about with the numbers and not being very clear about what they’ll do or won’t do exactly. For example, they said they’ll lift the boards but later said they won’t remove the old insulation, then said they would). I really honestly can't be arsed with them now due to constant back and fro!

£2300 for everything from another who says they’ll do it all, nothing left out.

I just find these prices a bit bonkers and considering doing it myself.

Is it possible? Is it hard? What would you do?

Or are the prices reasonable (more the second one).

Thank you

 

[Cubist]

You're right, they're thoroughly bonkers and the £2k+ one is the Full Contingency, Full HSA regulation compliant price for PPE including masks and hard hats and scaffolding and safety harnesses, etc. Run away from both of them! Assuming its the loft shown in some of your other posts the job is definitely well within the capabilities of any novice DIYer and the most technical elements will be pulling a few nails out of the boards and rolling up the old while laying the new insulation.

 

[lizziecupcakes]

Thank you @Cubist ! You and so many others on here always give me a good boost and confidence I can get things done myself. Thank you

Is it normal that fixing a house up is a bit overwhelming at times? I know others on here have much bigger projects and much more complex things to do compared to me. I am sometimes feeling quite unsettled in the house with it all, but as I do one job at one (sweet) time, it does make me feel a bit better. (sorry if this is oversharing!)

 

[lizziecupcakes]

also, this is a pic of part of the loft. It's fairly large in height on the party way, then slopes right down to the other side. I'm not sure what this type of roof is called. It's boarded already (mainly with floorboards rather than the loft boards you can get). There is a light and now a double socket (since I got the electricians in to add this). I don't have downlights or anything.

My main challenge will be ensuring good ventilation - is this just about leaving a gap somewhere? I did watch a B&Q and Knauf loft installation videos - I guess this is all we need to do?

i also think i will just use the Knauf brand, since it seems like a popular choice and cheaper than rock wool (which I'd prefer but can't afford). Has anyone used Knauf (link below)?

https://www.diy.com/departments/kna...Vb5JQBh01zhSqEAQYCCABEgJHwfD_BwE&gclsrc=aw.ds

 

[fernicarry]

£2300 for everything from another who says they’ll do it all, nothing left out.

I'll do it for #2299, I'll even bring my own teabags...

Its nuts money, but the yellow fibreglass insulation is thoroughly unpleasant stuff once you disturb it and a reputable contractor will be paying to dispose of it through a commercial service.

I've said it before, London prices. I have property in London and I get these kinds of silly quotes whenever work needs done. Its usually cheaper for me to fly in for the day and do the work myself but I guess enough people stump up otherwise they wouldn't keep trying it on.

You might need something like this for eaves ventilation.

For your target 300mm depth, you'll need to relocate those electrical cables so that they aren't buried.

 

[jamest]

I've used the Knauf stuff to insulate some stud partition walls as it is quite inexpensive (and was on special offer in B&Q) and is supposed to have good sound insulation properties (which was partly what I was after for those walls). What I can say is that you'll be needing the full PPE as it sheds a lot of unpleasant fibres that you won't want to be breathing in - not as bad as fibreglass, but still not nice. If I were going to DIY your loft, I'd probably be leaving the fibreglass stuff there and put the new stuff over the top because packing it into bags and getting it out of the house to a disposal site is a PITA and you'll probably never see it again once it covered (plus it won't be doing any harm).

 

[a twig]

At our last place I used the justification of the money saved on labour to spend a bit more on Thermafleece Supasoft for the reasons and approach that James mentions - much nicer to handle and just put it down on top of the old stuff

 

[Lacan07]

For your target 300mm depth, you'll need to relocate those electrical cables so that they aren't buried.

am I right in assuming you can place insulation on top of electric cables as long as they are clipped to a non insulated surface like a joist, something that is effectively a heat sink, whereas 'sandwiching' a cable between insulation is forbidden?

 

[fernicarry]

am I right in assuming you can place insulation on top of electric cables as long as they are clipped to a non insulated surface like a joist, something that is effectively a heat sink, whereas 'sandwiching' a cable between insulation is forbidden?

There's a range of installation "methods" that try to capture common situations. Nothing is forbidden as such but the cable's capacity could be significantly reduced.

For this loft would be method 101 as the cable is covered by >100mm of insulation. This is about a 35% derating.

You may be thinking of method 102 where the cable is touching the face of a plasterboard wall filled with insulation. Thats about a 25% derating.

Options are, 1) go up a cable size or two, 2) clip onto roof timbers to keep cable in free air (method C), 3) reduce rating of MCB to match.

Lighting circuits on a 6A breaker are unlikely to be affected, but if the ring main has taken a detour through the loft then it is potentially affected. Shower cables in particular should be kept clear as they tend to run at full chat for a period of time.

Full table here.

 

[Cubist]

Others have more experience than I with the insulation challenge but... can anyone here tell me why Lizzie should bother removing the wooden boards?

Seems a little pointless to me and the timber itself is an excellent insulator. Is damp a risk?

 

[paulc]

Others have more experience than I with the insulation challenge but... can anyone here tell me why Lizzie should bother removing the wooden boards?

If you drape the insulation over the boards (and/or joists), there will be a large air gap. Cold draughts can potentially blast through these gaps and negate any insulation benefits.
The first layer of insulation needs to be packed in to the space between the joists, getting all the way to the very ends where they rest on the outer walls. A second layer rolled out at 90 degrees completes the job.
If a boarded area is desired, use loft legs so that the insulation is not compressed. Many years ago, had the insulation in our loft topped up under an ECO scheme. They just rolled out the insulation covering the partial boarding that was up there. From then on, it was a crap shoot as to whether you were going to stand on a board or go through the ceiling.

 

[Cubist]

Is it normal that fixing a house up is a bit overwhelming at times? I know others on here have much bigger projects and much more complex things to do compared to me. I am sometimes feeling quite unsettled in the house with it all, but as I do one job at one (sweet) time, it does make me feel a bit better. (sorry if this is oversharing!)

It's certainly a darn sight more frequent than you may expect and most often it's due to the desire and ambition of the people concerned to transform the house they bought into the 'home' they want. Most start that journey knowing they will need to dip their toes in to the waters of repair and restoration starting with a little light decoration and minor repairs. Soon though their continuing exploration of the house produces a series of 'things to do' that can seem to stretch out in front of them like the view of a turbulent ocean seemingly full of rocks, sharks and other daunting hazards that would, and should, give anyone pause.

You, fortunately, seem to be one of the bright ones who steps back with the thought 'Am I ready for this?' before plunging in. Only fools rush in, as the saying goes, but you did the right thing and though you may not feel quite ready yet, there are many here prepared to help with your adventures in these waters. It can be fun.... and safe, honest!

 

[mh12]

Thank you @Cubist ! You and so many others on here always give me a good boost and confidence I can get things done myself. Thank you

Is it normal that fixing a house up is a bit overwhelming at times?

100%, Im in the same boat as you, doing a major refurb top to bototm although not living in the property at the moment as tbh its not to a habitable standard.
Being previously DIY/general house repair naive it has been a massive learning curve and at times bit depressing due to not knowing the best course of action to take especially with respect to insulating externak walls and ceiling on the top floor of the house.
This forum has been a massive help, I must say.
My 2p, deep breadths and enjoy the experience. I keep telling myself it will be well worth it once the project is finished and providing the children a comfortable living space.
Other advice, please keep asking away on the forum. You'll get some golden nuggets from experienced and knowledgable heads.

 

[mh12]

i also think i will just use the Knauf brand, since it seems like a popular choice and cheaper than rock wool (which I'd prefer but can't afford). Has anyone used Knauf (link below)?

Knauf do ecose insulation batts which are supposed to give off much less fibres compared to rockwoll. Dunno whethere they do an equivalent ecose type insulation in the form of a roll.
If the do well worth having a look OR alternatively you can consider the natural type insulation rolls but I suspect they might be more expensive compared with knauf type rolls.

 

[lizziecupcakes]

am I right in assuming you can place insulation on top of electric cables as long as they are clipped to a non insulated surface like a joist, something that is effectively a heat sink, whereas 'sandwiching' a cable between insulation is forbidden?

am I right in assuming you can place insulation on top of electric cables as long as they are clipped to a non insulated surface like a joist, something that is effectively a heat sink, whereas 'sandwiching' a cable between insulation is forbidden?

am I right in assuming you can place insulation on top of electric cables as long as they are clipped to a non insulated surface like a joist, something that is effectively a heat sink, whereas 'sandwiching' a cable between insulation is forbidden?

It's certainly a darn sight more frequent than you may expect and most often it's due to the desire and ambition of the people concerned to transform the house they bought into the 'home' they want. Most start that journey knowing they will need to dip their toes in to the waters of repair and restoration starting with a little light decoration and minor repairs. Soon though their continuing exploration of the house produces a series of 'things to do' that can seem to stretch out in front of them like the view of a turbulent ocean seemingly full of rocks, sharks and other daunting hazards that would, and should, give anyone pause.

You, fortunately, seem to be one of the bright ones who steps back with the thought 'Am I ready for this?' before plunging in. Only fools rush in, as the saying goes, but you did the right thing and though you may not feel quite ready yet, there are many here prepared to help with your adventures in these waters. It can be fun.... and safe, honest!

Thank you so much

 

[lizziecupcakes]

100%, Im in the same boat as you, doing a major refurb top to bototm although not living in the property at the moment as tbh its not to a habitable standard.
Being previously DIY/general house repair naive it has been a massive learning curve and at times bit depressing due to not knowing the best course of action to take especially with respect to insulating externak walls and ceiling on the top floor of the house.
This forum has been a massive help, I must say.
My 2p, deep breadths and enjoy the experience. I keep telling myself it will be well worth it once the project is finished and providing the children a comfortable living space.
Other advice, please keep asking away on the forum. You'll get some golden nuggets from experienced and knowledgable heads.

Wishing the very best with your refurb! I often feel like I have no clue what I’m doing and spend a lot of time researching before taking any action. This forum and all the experiences, advice and confidence boosts shared has been exceptionally important to me these past few months. I was on here before i even bought the house and now turning some of my research into action.

i sometimes think “what have i got myself into”, but on reflection, I do love the house more and more as we get things done a little at a time. You’re right, i need to remember to enjoy it!

i intend to share the journey on here as things progress, I hope it will help others as much as this form has helped me !

 

[mh12]

With respect to insulation I have found Historic England produce some fantastic guides for IWI and also roof/ceiling insulation.

Search All Publications | Historic England

Search our wide range of publications including books, periodicals and guidance documents.

historicengland.org.uk

Various guides, extremely informative and may help with decision making.

 

[lizziecupcakes]

You might need something like this for eaves ventilation.

For your target 300mm depth, you'll need to relocate those electrical cables so that they aren't buried.

Update: we have decided to put loft insulation in ourselves and we are well on our way to get it done soon

hi @fernicarry - I have just cleared my loft and working on the loft ventilation part of this job over the next couple of days to prevent any potential condensation issues.

I have ordered these (Felt lap vents) to put between the bitumen for airflow. Here's a youtube video in case it's helpful to anyone else!

Thanks for recommending the eaves panel vents in your comment! I'm probably a bit silly here, but I can't actually see whether i have eaves vents or not. I just had new gutters installed and my soffits and fascia are black, matching the gutters. It's quite high up so i can't see any vents at all with the naked eye; I'm pretty sure I don't have them.

I've messaged my roofer to ask if he knows and has seen them and will await his reply tomorrow. What I do know is that a new roof was laid in 1990 by the previous owner and there is bitumen felt, concrete tiles, with some ventilation "pipes" (Ive attached a photo of the roof for reference - no idea what these vent pipes are called) . There is currently about 100mm of loft insulation laid in by the previous owner. I can't see any condensation issues, and the roof smells fine too. Soooo, I think when I top this up, it should be fine with only the Felt lap vents I've linked above (if there's no eaves vents).

My question is: in a roof built in the 1990s, is it unusual not to have eaves vents? I have a feeling I don't have them in my roof. My partner thinks we should just buy some Eaves Panel Vents (your link here) anyway just in case lol... but I don't think it's a bad idea and won't hurt since we are now doing the loft insulation ourselves and the price is minimal compared to what we would have paid.