1930s Semi Refurb - Part 4 of ... (Edition: Loft Insulation)

[dlockers]

Hi folks,

Me again - given the turn in weather, the boiler man being booked for early November, and a Christmas visit from my mum planned - I am thinking I may hold off on any major progress on the bathroom until the new year. Cue the perfect opportunity for a low effort (lol), high impact (lol) job - loft insulation.

At the moment I have a lath and plaster ceiling, and about 60% of the loft boarded. The roof is the original 1930s clay tiles on wood (no felt). It is cold up there, and I think the lathe and plaster ceilings offer little to nothing in terms of insulation. There is some fibreglass looking stuff up there in places at the moment, but not very much and clearly a half job (maybe just for one of the bedrooms).

I have seen a few products that suggest raising the joists to pack in (but not squash) rockwool type stuff, and silver barriers stapled to the roof interior. I also found this chap who goes into detail on the theory and provides some tips, so this'll be my default guide.

What's the general craic on doing this job? Where do I begin? What systems have you used and is there a way to do this inexpensively?

Thanks!

 

[ANDARIAL]

If you do end up using fibreglass/rockwool use adequate protection,overalls and a good mask and gloves
HORRIBLE stuff to lay,i had 40 years on and off using this stuff.itching and coughing .MASK is essential imho

 

[Mason-]

Funnily enough I did this 3 weeks ago. Loftlegs are what you're after if you want boarding. Depending on how much you want, get Loftlegs XL.

I'm guessing yours is similar to mine where the existing boarding was directly on the joists, squishing any insulation there and not doing a very good job. I had to lift the old boards, put the legs in, new insulation down, and reboard over the top.

Photos:

Spoiler

1st Photo, Can see the old boards on the left. Legs in place on the right.


2nd Photo you can see the insulation between the legs, and a few boards down.


3rd Photo, all done...

In terms of material, you can get 1200x600x18mm boards. If you can get the boards easily into your loft, get the 2400x600x22mm boards, far more solid and obviously much less boards. For me it was the difference between laying 10 boards vs 40. It's also more cost effective. But I know a lot of people struggle to get them into their loft and so have to use the smaller boards. It was a weekends worth of work and bloody hard work but should pay dividends, kind of wish I did loft legs XL now... but this is a lot better than what was there before.

This is what I bought from Wickes, also had to buy another pack of screws. Had 2 spare boards at the end so could have saved a bit, and obviously depends how much you want to board. Insulation is pretty cheap. And as you can see from the last photo had plenty spare and a whole unopened roll spare too. I didn't need the timber either, I bought it just in case I needed to do some reinforcing.



The insulation does itch but only for a day really so you can wear long sleeve tops and tracky bottoms but you will get so hot. I just manned up and did it in shorts + t-shirt but it was still 20+ then.
Oh and my last tip. Get a head torch and knee pads!!!

 

[dlockers]

Top man, thank you! Did you do anything special around wiring/services?

Are the loft legs solid?

Did you do anything about the roof itself? I have seen a few images pop up of a lady stapling some kind of foil to the roof rafters?

 

[Mason-]

Top man, thank you! Did you do anything special around wiring/services?

Are the loft legs solid?

Did you do anything about the roof itself? I have seen a few images pop up of a lady stapling some kind of foil to the roof rafters?

No, maybe I should have I know you can get special hole saw bits that cut access holes out and you can buy caps for the holes. Like this: https://www.youtube.com/watch?v=tQT3ztxXj9g I might do that so I can access all the lighting wiring.

I was skeptical about how strong the legs would be but honestly they are solid, can't talk for the XL but I assume they'd be the same. Feels more solid than my first floor floorboards.

No I didn't, it has a membrane (mines a 1950s, the difference 20 years makes eh?). I don't really have any advice for the roof, all I'd say is whatever you do consider ventilation. Generally people insulate around the rafters and have a 'hot roof', or they insulate at the joists and have a 'cold roof'. In the cold roof case you need to make sure the loft can vent, so whatever you add maybe add some soffit vents.

 

[Freefaller]

Depends if you want a warm loft or a cold loft. Warm loft (i.e. rafter insulation) is usually used if you want to live in the loft or store more delicate stuff in the loft. Cold insulation is obviously a lot cheaper and "easier" still a miserable job to do.

Obviously if you need/want to board it you need to make sure you don't squash the insulation else you mitigate the point of it.

 

[dlockers]

Thanks chaps - RE: Cold/Warm loft, who decides?

I have a roof as pictured here, so I am unsure I have traditional soffits that I can vent:

Improving the Thermal Performance of UK 1930s Semi Detached Houses

Sharing the experience of improving the thermal performance of a UK 1930s semi detached house and suggestions for what could be done…

peter-wurmsdobler.medium.com

Loft may be a living space in many years time but not yet.

 

[Freefaller]

Thanks chaps - RE: Cold/Warm loft, who decides?

I have a roof as pictured here, so I am unsure I have traditional soffits that I can vent:

Improving the Thermal Performance of UK 1930s Semi Detached Houses

Sharing the experience of improving the thermal performance of a UK 1930s semi detached house and suggestions for what could be done…

peter-wurmsdobler.medium.com

Loft may be a living space in many years time but not yet.

It's up to you really. The rafter insulation is more expensive. You also need to leave at least a 50mm gap (I think it's for cold bridge) but also help with reducing the build up of damp. If you board it out it'll make it a more useful space, having some insulation above the boarding will be useful for sound proofing and so on, but it doesn't need to be the 270mm thickness if you do decide to do rafter based insulation.

 

[Mason-]

Soffit vents aren't the only option, you can get vents for the felt/membrane (google Felt Lap vent), as well as vent tiles. This is for the cold roof solution, I don't know what you do in the case of a hot roof because obviously ventilation leads to drafts and it won't stay warm. I think that's why cold lofts are more common, heat your home, insulate as much as possible around the joists, and allow the space above that to be cold and ventilated. Means you're warm where you spend most of your time and don't get damp problems in the loft.

Edit: I forgot to add if you have a gable wall anywhere you can just use air bricks too.

 

[dlockers]

I'll have a proper look up there in due course. I think I'd stick to cold roof.

First job, I need to swap the dodgy lightbulb for some LED lighting as well as it is really too dark to do anything at the moment.

Thankfully its full of old carpet which I think was used to cover the rafters and avoid boarding out the rest of it ! I guess with the 300sqft workshop it was low down the priority list.

 

[Buffman]

I used loftzone flooring and can see some pics of it in the below thread. I just did fairly standard cold roof construction ie increasing insulation depths and raising the level of the loft boards

How to fit a good in line bathroom fan in loft and reduce noise?

Hi all, Im renovating my bathroom and want to put a centrifugal fan in the loft. Ive already got the electrics sorted I just want to know best way to dampen noise? Should I make a timber frame hanging from the purlins? Could I mount the fan vertically and point it straight out the loft...

forums.overclockers.co.uk

 

[dlockers]

Hi guys,

As per man jobs thread - I have made a crack at the loft today (minor) and took some measurements. Roughly, excluded the very front with the funky roof, I have about 28m2 - or 4.2m * 6.6m.

The hatch itself is a nightmare as it opens out into the bathroom of all places.

I'm thinking
1) Order a tonne of bin bags and clear out the mess
2) Vacuum the entire thing
3) Get a decent quantity of framing timber to add noggins to what are presumably, just basic ceiling joists? (will these support my weight?!)
4) Buy some loft legs
5) Board
6) (in the wrong order) - put some PIR down the hips of the roof (is that what they are called?)

My only concern is I may need to get to the lighting circuit of the rooms beneath, so I am a little turned off by the thought of tongue and groove. I guess the obvious answer is to do any light wiring beforehand, but I am a million miles off getting my head in gear about that.

Can anyone coach me on an easy way to get this all nice

https://i.imgur.com/KxQ9L7p.mp4

 

[danlightbulb]

Do you have solid internal supporting walls? If so, you can plan to lay additional joists on these to support the t&g.

Also I have read that the OSB loft flooring is better to than the chipboard stuff, and not much price difference.

When I do be this job I'll be adding new joists across the existing supporting walls rather than using loft legs. Additional insulation can go in between these extra joists.

 

[Mysterae_]

Good luck @dLockers that looks like quite the job!

I'll probably reiterate a few of the points made by others but here's mine:

1. I'd definitely clear out and get rid of all the old stuff, it'll be way past it's thermal best. Not sure of the insulating properties of dust .
2. Before splashing out on loft legs research a little on youtube - I've seen people make there own supports using 2x4 or whatever. The cheaper plastic legs have been known to bend and twist.
3. You'll need ventilation up there or you'll suffer from condensation in the loft space during winter. You would be surprised how much moisture can seep it's way through the ceiling, insulation and the little holes the wires for ceiling lights make. A few ideas about ventilation have already been mentioned.
4. Make sure you're loft hatch has a damn good seal, especially since it's in your bathroom - linked to the above point moisture will most definitely make it's way in to the loft.
5. Ventilation again - don't put too much stuff in the loft when you're finished. You need airflow through the loft, for example eave to eave especially if you have soffit air vents. Plus there's the concern of putting too much weight in the loft.
6. Might sound obvious but use screws when affixing the boards (the previous owners of my house used nails muppets).
7. Be careful of dropping things in the loft - not in case you make a hole but to stop any impacts causing the plaster in the ceiling below to fall off!
8. Check the existing wires for their sizes as you may need to uprate them due to the additional insulation (though unlikely). Also check for any dodgy wiring connections made by the previous owner!

You could fund this project by selling that picture of Jesus on blue paper that I spotted at the 3 sec mark in your video. It could be Che Guevara though, can't quite tell .

 

[dlockers]

Appreciate the replies chaps, thank you.

Will certainly be clearing the lot out. If 2x4 framing timber is still the same cost, it will actually be cheaper than loft legs so I am tempted to go that way. Some of the timbers are already twisted so I can't imagine loft legs will be straight forwards in any case.

I have lathe and plaster ceilings and the one room is battered to heck, so also noted on being careful. I need to overboard and plaster (in due course).

You've probably put the nail in the coffin for me W.R.T swapping the loft hatch for a proper modern sealed unit.

My biggest concern is ventilation - if I insulated the "hips" of the roof (still unsure if this terminology is correct) - then I won't have much natural airflow. Other than the funky bit of my roof, I don't really have "eaves" as the roof comes down so low to the walls. Potentially I can put vents in what I have, but it won't be "back to front" ventilation like what may be required.

Wiring looks legit - but worried about losing access. Maybe I'll batten + board in squares so I can lift up entire sections without issue.

Will dream on it for a few weeks (y)

 

[Mysterae_]

I might have overstated the need for airflow - as long as no moisture gets up there in the first place then it's less of an issue but still best practice.

In my old house the felt of the roof was literally dripping with condensation, so much so I thought the roof had a leak. It was fixed by addressing a lot of the issues above (eave vents blocked, poor loft hatch seal, too much crap stored there). Felt doesn't absorb much if any water but wood does and it can go un-noticed a lot of the time. It can create mould too.

 

[Freefaller]

Would that sort of loft suit a warm loft system instead? i.e. insulate directly onto the roof rather than the floor? Means he could board up the floor with less insulation and generally I think it allows for better air flow?

 

[dlockers]

Would that sort of loft suit a warm loft system instead? i.e. insulate directly onto the roof rather than the floor? Means he could board up the floor with less insulation and generally I think it allows for better air flow?

I'm just nervous that the wood will rot through as there is no felt...

 

[dlockers]

Subject to someone telling me to stop... I'm thinking of starting with 8 rolls of this stuff.

https://www.diy.com/departments/knauf-eko-roll-loft-insulation-roll-l-4-83m-w-1-14m-t-200mm/182147_BQ.prd

The first job may be to move the hatch though so I can get the 2.4m x 600m boards up there... I bet they weigh a tonne as well.

 

[Kohaashi]

Where will you be moving the hatch to? We are currently in the position of moving ours from the bathroom to the back bedroom.

Also a 1930s semi.