Insulating a room - would you DIY?

[ShadowMan]

Having moved into our new home in Feb we always planned to update the office and games room behind the garages which were converted in the late 70s. Currently they are just block and brick with 25mm battens and then some wood sheet panelling. It’s not the most comfortable room in the house.

Total liner length of the walls is about 20m. I have had a quote from a builder who wanted nearly £4K to take it back to brick and then put up celotex and make good with a plaster finish. I’m tempted to do most of this myself however as it’s something I would like to do and think I could. Am I in for a world of hurt trying to DIY dot and dab celotex install?

I have asked for a pre app inspection from building control who are coming Monday so they can specify what thickness I would need etc.

Would you attempt it yourself or pay the extra to get pros in to do it.

Final spanner in the works could be a lack of a building control cert for the garage conversion. I have raised this with the solicitor who did our purchase but they are confident that as the planning permission (which I have the cert for) and work was done in 1977 then I wouldn’t need a cert as it was before they were compulsory. Waiting for confirmation in writing though.

 

[ShadowMan]

I have asked 2 other builders to come quote but neither has showed up yet. Only been a few days so will give them a chance.

material wise it’s around 20 sheets of celotex at £50 each and then some 2x4 and other ancillaries for battening out 2 walls. Probably £1500 in material maybe a bit more. Need to do a bull BoM but I would expect to be saving probably around £2k doing it myself at least. It doesn’t need to be quick as they are spare rooms really at the moment.

more worries if it’s a doable DIY project. I’m fairly competent and will tackle most things but don’t want to spend money and waste it really. YouTube makes it look easy but that is what YouTube does lol

 

[ShadowMan]

There is electrical in place already but my dad is an electrician so he will come in and add more as needed during 1st fix. Its also not on a ring we don't think just a 20A RCD from consumer so may get it updated. Also having a plumber put in new radiators and he has already dropped pipework into nearby area for access.

I'll get a pic uploaded of its current state, may start demo on monday too as having a skip delivered to clear out some other rubbish.

 

[ShadowMan]

Pretty sure the Celotex has built in VP with being foiled twice per sheet as long as joins taped properly but I’ll look at a separate layer too.

Dad is fully registered and set to update and move the consumer unit anyway as it’s quite low down and 1 years old with only 3 circuits covered by RCD. Would have been done already but lockdown happened. He’s coming next week do install some lights for me though.

I’ll keep watching some more videos. Doesn’t sound like anyone thinks it would be beyond a DIY project at least.

 

[ShadowMan]

So finally got a panel taken off the wall to see what exactly was underneath and picture below

Its 20mm x 45mm softwood with a 3mm ply panel over the top held in with panel pins. The battens are on the wall using old style clout nails.

Current thought is to build out a frame with 38mm x 63mm CLS studs with top and sole plates from the same. Will add noggins and then fill the space with Rockwool RWA45. Over the top will add 50mm of Celotex (or cheaper equivalent with a foil VLC) and then top with 12.5mm plasterboard.

Yes I will lose a few inches on each wall but think it will be worth it.

Anything I need to look out for? 2 of the 8 walls to do are external single skin so will probably put a breather membrane between the studs and brick.

 

[ShadowMan]

Not much to update. Ripped 1 of the offices out to get it back to brick and had a 2nd visit from a builder to do a final quote before I make a decision on doing it myself. Walls are clean and dry and I really don't think it will be a major job to do. 50x75mm CLS with rockwool filler and a breathable membrane on the outside walls all topped with 50mm foil faced PIR and then plasterboard.

Electrician due at weekend (Dad so free) to get sockets sorted and ensure its all on a ring and change it to a 32A RCD from 20A even if we have to rewire.

Plumber hopefully next week to put in a radiator with pipes so I can work around it with the insulation.

 

[ShadowMan]

Just putting down a high tog underlay and then laminate or carpet (not decided yet). The floor is already raised 6” above garage floor so assumption is that it is an insulated slab. It’s not too cold really.

ceilings are being boarded over or redone using PIR too as there is room to lose there and may as well.

 

[ShadowMan]

I'll have a look but the floor was poured level with the living room so would raise floor above rest of house and create a step at the threshold. Could the floor be tackled after or should it be first to ensure it goes under the walls?

 

[ShadowMan]

At the moment the carpet in there is just stuck to the concrete so I am hoping a decent underlay will make a difference at least.

 

[ShadowMan]

Mainly as I am more confident with drilling into the wall and levelling battens than doing dot and dab and getting it plumb. I was going to fill the battens with more PIR but seems easier to use rockwool batts and fill it in.

Builders have suggested dot and dab and if I pay to have it done it will be that way as trust them to do it better than I could!

 

[ShadowMan]

Well got the quote from the builder and as expected much higher than I wanted and actually even higher than the guy who didn't even want the job.

I have ordered materials (some) and going to give it a go myself. Have decided to make the mess and fit 50mm PIR between the battens instead of rockwool so will be 50mm inside CLS timber and then 50mm topped and foil taped with plasterboard fixed over the top of the lot giving 100mm of PIR total.

Currently trying to course a decent breathable membrane for the outside walls to put up behind the framing. I'll DPC all of the timbers in contact with floors just incase.

Excluding screws, membrane, foil tape and DPC I have so far spent about 1/4 of the quote from the builder who was going to dot and dab the walls. I think I'll do it all for around 1/3 of the price which is a significant enough saving to try it myself.

 

[ShadowMan]

Brought the ceiling down over the weekend as dad wanted it out the way to run cables. Electrics in the office aren’t a ring but just a 20A radial circuit. Going to leave it as is for now and upgrade to a ring when I get the board changed possibly. Have added 2 extra double sockets to the room for better positioning when it’s my office.

With the ceiling down I can see the flat roof was built as a cold roof so now going to add some PIR between the joists and then below them before plasterboarding. When bringing to down there was some old fibreglass loosely placed up in the void. New setup Should provide 100mm of PIR at ceiling level. There will be a 6” void above and there is airflow into the garage over the joining wall so not worried about condensation. Will add a membrane above the PIR anyway and the foil facings will be taped to form a good VCL anyway on the ceiling.

Waiting for plumber to come run pipe work for radiator and the materials for walls to arrive on Tuesday hopefully. Should be able to make a start next weekend hopefully.

 

[ShadowMan]

As I said above, ceilings are down but I still have a few nails to remove from the joists. Trying to decide if I should do ceiling first or build up the walls framing. I am probably going to redo the supports for insulation/plasterboard between the joists as they look fairly old and random. For framing I have been researching and looking to do a California corner to allow the plasterboard to sit nicely. Seems the cleanest way.

Anyone have any tips on ensuring/making the frames square and plumb? I have seen video's about straightening a wall by making cuts and adding wedges but harder to do when its so close to a block wall. Mainly I mean for taking any twist/bend out of the timber. I'll be wedging out from wall to get plumb overall as required.

Flat pack office in the garage:

 

[ShadowMan]

Quick update and I've managed to get a bit done slowly whilst doing other things. Frame is up (3/4 walls) and the initial layers of insulation are going in. It has certainly helped a bit in the warmer weather as the single skin walls are hot to touch on brickwork after a day of direct sun but after the foam is in you can't feel a thing. Ceiling will have another 50mm layer below joists before plasterboard so should be plenty warm/cool for now.

 

[ShadowMan]

Well another update for anyone interested in that the majority of the work is done. Walls are fully framed out with 50mm Xtratherm between the studwork. Have added the 50mm Xtratherm layer over the top and VCL complete by using aluminium tape on the joints all around. Floor will be finished with a VCL and insuataing layer before a laminate floor is layed down.

Plasterboard hasn't been too hard to do but I did need help to get a full sheet on the ceiling. The rest I have done solo. Waiting on plumber to install pipework for radiator and then will finish sealing up the room. Plasterer is booked but struggling to get any plaster. Hoping to get hold of 4 bags tomorrow from local merchants who are due a delivery. Will be getting the window sill at the same time too.

 

[ShadowMan]

Overall lost around 110-120mm on each wall but maybe a bit higher in places as I squared up the room too whilst I was at it. Its a lot to lose but as 2 walls were single skin brick it needed doing. I've also lost around 60mm of head height too on the ceiling but its a cold flat roof install so again needed doing. I'm happy with it for an office space and is still usable.

 

[ShadowMan]

It is certainly a lot more stable. Even with the sun shining on the walls all day it does not get anywhere near as hot as it did! Hoping its the same for the cooler months.

Was hoping to get plaster today. Local merchants due a delivery. Promised me a call. They didn't ring so I rang them this morning and this afternoon. Nothing available. Going to be bare plasterboard for a while at this rate!

 

[ShadowMan]

The tape was just a cheap one from Amazon really. It seems to have done its job and stuck down OK and is wide enough to seal and create the VCL I needed. I wouldn't necessarily recommend it but I've only done 1 room so mainly for that reason. I've got half a roll left so may try another for the next room I do in September.

Supplies seem to have picked up today. Local merchants I have used for everything got a delivery of plaster and called me as they promised too. Booked 4 bags for delivery on Friday with my window sill and 6 lengths of corner bead. Booked in my plasterer for Monday 27th and the plumber has promised to come early next week to finish the pipework for the radiator. Will leave it empty and mount it all after plaster and painting.

Ikea due to deliver desks on Sunday 2nd August so gives me a few days after plaster to let it set and get it painted. Nearing the end now!

 

[ShadowMan]

Forgot I never added anything on here. Pic below is after building the desks. There is a billy bookcase with doors and space for a 2nd behind camera. Room has a lot of junk in it now whilst working on other rooms as it has become useful for storage.

I use the left hand desk for work, centre/corner is my own PC and the right hand side is for painting/airbrushing. The plasterer did an OK job but left some things I wasn't fully happy with. May do some more sanding/smoothing in future but its mainly on the ceiling and I don't see it day to day.

Just reminder of original room after stripping back

Finished Room

 

[ShadowMan]

Thanks. I actually got the blue to match the Secretlabs chair I have. Took the cushion into B&Q and got them to sample match it. Will be using it to accent some shelves and bits too. The room was a lot of hard work but certainly worth it. I have a quote to add AC now too as WFH seems to be a long term plan so may need it.