Mike's ext'n & renovation (solar panels)

[Mike G]

To tie the brickwork into the studs on either side so it doesn't just fall out?

That's it exactly.

The oak will shrink away from the visible mortar line. If this was straight through, then you would see light through from the next room, and there would be nothing to stop the whole panel just falling out. Putting in a rebate means that this can't happen, and it will also mean there is a "wall" of dried mortar as backing for the repointing which will be necessary in a year or two.

 

[big soft moose]

Whats the reason for using brick in the panels mike ? I'd expected that they'd be something like wattle and lime plaster (Not that i know what i'm talking abbout of course )

 

[Mike G]

Herringbone (or basket-weave) brick infill panels are not only absolutely traditional, they also look great. It's for the latter reason that I'm using them. There will be plenty of plastered panels when I start renovating the old part of the house.

 

[Mike G]

I've been getting a bit fed up with how long this oak work is taking, but there is no way of doing it quicker other than to hire a chain mortiser........so I plodded on. This is a detail from one of the studs in the oak wall between the lounge and the kitchen. We'll start with a simple guessing game. What is this all about?



I finally got everything finished enough for a trial fitting, and stood it roughly in place:



This is why it is called a trial fitting :



On inspection, it turned out that each of the top and bottom plates bows in the middle by about 2 or 3mm. Combined, we have a nasty joint. So I built a quick frame to hold the heavy top plate up in the air whilst I took the studwork apart, tiffled with a couple of joints, and put it all back together again:





OK, so here is a look at the question again, but this time in-situ:





That's it for oak work for the time being, although I have just ordered 8 more pieces, and sent one low-quality piece back for replacement. Now......

Insulation.

I toddled off in the van to a local stockist of "seconds" quality Celotex. For those who don't know the stuff, it is a rigid PIR insulation, roughly twice as thermally efficient as mineral wool ("fibreglass"). I could only fit 7 boards in the van, and I think I need 9 for the roof. Never mind, there is lots of other insulation i require, so I will be going back a number of times:





Most of the boards are perfect, but one or two have creased aluminium foil on one side or the other, and one was over-long. They are roughly 60% of the price of the same boards from a Builder's Merchants.

This insulation is going between my rafters. The rafters are 195mm deep, and it is a requirement to have 25mm of airflow over the top of insulation in these circumstances (careful with that fact: check with your Building Inspector first, because it depends on the pitch of the roof, the type of membrane, and whether the membrane has been laid tight or the more traditional sagging). So, I bought the nearest available board, 165mm deep. That is the equivalent of approx 330mm of "fibreglass"......but that isn't the end of the roof insulation: there will be 50mm of Celotex across the underside of the rafters, too, so my roof will have roughly the equivalent of 430mm of mineral wool (fibreglass).

When fitting this stuff, I always specify that it must be cut undersized and spray foam applied into the gaps all round. Done well this is a great method, but it is impossible to tell if a contractor has filled the entire depth of the insulation, or just put a bead on the surface. I decided to try something that I have been thinking about for a while: cutting the sides of the board to an angle, such that they offer a close fit at the back of the board, and a gap for foaming into at the front. Hence the non-vertical cut:



This detail turned into a nightmare, and I am going to have to re-think it. This is at the top of the rafters:



I couldn't get a well fitting board to go up and over the lip in the ridge beam, and then sit back down again level with the underside of the rafters. There is no way of getting hold of it to pull it back down again. All the while I was fighting with it, dust from the insulation was getting in my eyes, and it stings like crazy. Anyway, here are a few boards fixed and foamed in place:





At this rate it will take more than a day to insulate the roof.

 

[billybuntus]

At this rate it will take more than a day to insulate the roof.

Nice progress Mike. I'm 90% way through renovating a rental house and I'm pig sick of it. Nothing on your scale but I pulled off some skirting last night and about 3 square meters of plaster came with it....tedious.

Try not to think of the time the insulation is taking but think of the little energy your expelling and how much it will save throughout your lifetime. Worth every kilo joule!

 

[Mike G]

You're dead right, BB.....

 

[Mike G]

Well, it's been a while.

I have lost a week over the last 10 days, messing about insulating the roof. It was a dusty, filthy, horrible job. I've done it as well as I think it is possible to do it, and I'm not at all happy with it. I will never again specify this on any jobs I draw, but having started I was committed, and at least it is now done and out of the way.

This is typical fitment between rafters. Note the taper cut to the boards, giving a gap which is relatively easy to get a foam gun into, but yet allows the foam to expand into a taper and hopefully fill it fully:



Top and bottom both had cuts to them (ie they aren't just square), so this is the next stage:



I typically offer each piece up 2 or 3 times, adjusting until the fit is OK, then I wedge it in place, and apply 4 or more squirts of foam which glue the board in place:



I then come back later once those holding blobs of foam have gone off, take out the wedges, and fill all the gaps with foam. You can't do this before the board is fixed in place because the foam gun nozzle would move the board out of position:



The next step is to trim all the excess off, fill any bits you might have missed, and then finally, apply a 50mm board to the underside of the rafters. This is just nailed here and there, because it will be held properly later by the screws which hold the plasterboard:





So finally the job is finished, and ready for plasterboarding:



Thank goodness for that. I've hated every moment doing it, especially with all the dust making my eyes red and sore, and especially knowing that as well as I can do it it remains a second rate job.

 

[StevieB]

Why do you feel it is a second rate job Mike? Seems to me you have sealed any gaps and then overboarded to eliminate any thermal seams leaking heat as well. What would be a better alternative if you are not going to specify this method on any future builds?

Steve

 

[Mike G]

The problem is this Steve. You can't actually see if you have filled the gaps to full depth. It is perfectly straightforward to put a superficial bead along the surface, say an inch deep, which fully seals, and I would bet my bottom dollar that that is exactly what gets done on site. So, I may have done a decent job, but I can't be sure.

My alternative from now on will be spray foam insulation, sprayed in-situ. They use a 2 part foam, rather than an air-drying one, and can accurately build up the depth to the thickness of the rafters (there would need top be a backing board to keep the air gap under the roofing membrane). There would be no question at all that all of the rafters were fully filled, and no voids created. Have a look here: http://www.sprayfoaminsulation.co.uk/gallery/domestic-roofing-and-insulation.aspx

 

[RogerM]

The problem is this Steve. You can't actually see if you have filled the gaps to full depth. It is perfectly straightforward to put a superficial bead along the surface, say an inch deep, which fully seals, and I would bet my bottom dollar that that is exactly what gets done on site. So, I may have done a decent job, but I can't be sure.

My alternative from now on will be spray foam insulation, sprayed in-situ. They use a 2 part foam, rather than an air-drying one, and can accurately build up the depth to the thickness of the rafters (there would need top be a backing board to keep the air gap under the roofing membrane). There would be no question at all that all of the rafters were fully filled, and no voids created. Have a look here: http://www.sprayfoaminsulation.co.uk/gallery/domestic-roofing-and-insulation.aspx

I suspect that not only do you do yourself an injustice, but also over estimate the care that would be given to this on site by a subbie. I did something similar on my extension, and you're right - it's a horrible, dusty, time consuming job where all your care and attention gets covered forever and the end user never gets to see it. I just used the usual squirty air drying foam and taped the joins with metallic tape and my builder said he'd never seen anyone do the job so thoroughly, and yet, like you, I felt that there were still shortcomings in what I had done. Rest assured it will be better than 99.9% of similar jobs done out there, and that should be good enough!

 

[Wizard9999]

The problem is this Steve. You can't actually see if you have filled the gaps to full depth. It is perfectly straightforward to put a superficial bead along the surface, say an inch deep, which fully seals, and I would bet my bottom dollar that that is exactly what gets done on site. So, I may have done a decent job, but I can't be sure.

My alternative from now on will be spray foam insulation, sprayed in-situ. They use a 2 part foam, rather than an air-drying one, and can accurately build up the depth to the thickness of the rafters (there would need top be a backing board to keep the air gap under the roofing membrane). There would be no question at all that all of the rafters were fully filled, and no voids created. Have a look here: http://www.sprayfoaminsulation.co.uk/gallery/domestic-roofing-and-insulation.aspx

I suspect that not only do you do yourself an injustice, but also over estimate the care that would be given to this on site by a subbie. I did something similar on my extension, and you're right - it's a horrible, dusty, time consuming job where all your care and attention gets covered forever and the end user never gets to see it. I just used the usual squirty air drying foam and taped the joins with metallic tape and my builder said he'd never seen anyone do the job so thoroughly, and yet, like you, I felt that there were still shortcomings in what I had done. Rest assured it will be better than 99.9% of similar jobs done out there, and that should be good enough!

I don't think being better than the general out turn is Mike's point(s).

1. If others do a really bad job, I think it is little comfort to him that his work is better than that bad 'benchmark' if it still turns out his work is not as good as he would like. It is his house, he wants it as good as it can be, not just a bit better than a third party builder would have done.

2. As an architect I think he is looking to specify a solution for clients that is inherently more likely to result in a better outcome, rather than leave it to the diligence of the person doing the job. For that his professionalism is, as ever, to be commended.

Apologies, if in effect speaking for you I am out of turn Mike.

Terry.

 

[9fingers]

+1 Terry,

You have expressed my thoughts exactly!

Bob

 

[RogerM]

My apologies if I implied that doing better than the general gash job done by a subbie should be regarded as good enough. Obviously Mike is seeking perfection. My point was that he has clearly taken every measure possible to achieve that, but most of us would agree that with most jobs, if tackling it again with the benefit of hindsight and experience, would do something differently, however small, or could do the same thing with more skill, which I suspect is what Mike was saying - no doubt he'll confirm if that misrepresents his aim.

Having done a similar job myself, and having looked at what Mike has done on his own project through this thread, I think I can say with a fair degree of certainty that what he has done puts the job in the top 0.1% and I don't think I am recommending acceptance of a gash job by saying that.

 

[Mike G]

I don't think being better than the general out turn is Mike's point(s).

1. If others do a really bad job, I think it is little comfort to him that his work is better than that bad 'benchmark' if it still turns out his work is not as good as he would like. It is his house, he wants it as good as it can be, not just a bit better than a third party builder would have done.

2. As an architect I think he is looking to specify a solution for clients that is inherently more likely to result in a better outcome, rather than leave it to the diligence of the person doing the job. For that his professionalism is, as ever, to be commended.

Apologies, if in effect speaking for you I am out of turn Mike.

Terry.

Perfectly put Terry. Saved me some typing

 

[Mike G]

My apologies if I implied that doing better than the general gash job done by a subbie should be regarded as good enough. Obviously Mike is seeking perfection. My point was that he has clearly taken every measure possible to achieve that, but most of us would agree that with most jobs, if tackling it again with the benefit of hindsight and experience, would do something differently, however small, or could do the same thing with more skill, which I suspect is what Mike was saying - no doubt he'll confirm if that misrepresents his aim.

Having done a similar job myself, and having looked at what Mike has done on his own project through this thread, I think I can say with a fair degree of certainty that what he has done puts the job in the top 0.1% and I don't think I am recommending acceptance of a gash job by saying that.

No need for apologies. You were bang-on with all your comments.

 

[StevieB]

Thanks for the explanation Mike. I have seen the spray insulation before but never used it. One way to check how good your job is would be to buy or hire a thermal imaging camera and see if you can locate the filled joins - might give you peace of mind or nightmares depending on what it shows!

Steve

 

[big soft moose]

I'm obviously missing something here (not unusual) but why the wedge shaped gaps and the foam at all - when i built my office (and god knows that was a job to make "bodgit and scarper builders inc" look like isambard Kingdom brunel) I just cut the kingspan to fit between the studs as a tight push fit and whacked it in with a rubber mallet (or a piece of 2x4 if i couldnt find the mallet) and then plaster boarded over it.

I know there must be a good reason mike isnt doing it like that (other than that he isnt a bodging halfwit like me) but I'm damned if I understand what it is

 

[Mike G]

Because it is 165mm thick, Pete, and there is no way you can achieve a good fit and persuade that thickness of Celotex into place: the friction is just too much. It's one or the other. If it were 100mm thick, then no problem.

 

[chataigner]

A question for Mike re this type of insulation - my house is early 19thC and the rafters are simply trees, roughly adzed to shape, so both curved and irregular. It will be impossible to fit the panels closely, but could I use your system, recognising that the gaps will be quite large ?

The budget requires a DIY operation, so I guess the spray infill is not an option.

 

[9fingers]

You might be able to DIY? http://www.foamseal.co.uk/diy-spray-foa ... ts_new.php

or at least use this system instead of large numbers of rattle cans.

That was just a first hit on google, there may be other/better options

Bob

 

[Mike G]

Yeah, you could David. You must allow an airgap over the insulation, though (25mm if you have a breathable membrane, 50mm if felt, but the latter requires vents top and bottom). Just take your time, and buy yourself a foam gun and plenty of cans of foam..........or you could follow Bob's link, and see what that produces.

 

[Mike G]

After a damn good tidy up of Celotex dust and scraps (literally about 2 cubic metres), focus turned to the walls. Windows are arriving next week, and I also will be starting the inner skin of blockwork any day. The detail at the window surrounds (internally) is very easy, just a frame of 100 x 50 nailed to the inside of the frame, to close the cavity to the inside of the block skin. There should be a 5mm gap to the back of the blocks if I have got everything right:



Here is a quick view of the rear of the house, with scaffold out of the way. I'll copy this along when the windows are fitted, as a comparison. Windows make a dead facade jump into life, and I always think of them as the eyes in a face:



In preparation for insulating the walls, I had to move quite a lot of stuff, the sweep all the horizontals clean, and then go around with an air-line, blowing the remnant dust away. So this simple "before" shot masks a hour or two of work:



Cutting the insulation to width:



After:





All of downstairs is done, and a third of upstairs. It went much quicker and easier than I thought.

 

[Wizard9999]

Cutting the insulation to width:

Mike

Is that rolls of loft insulation you are using, rather than the cavity batts you used on the workshop? Will it sag at all?

Terry.

 

[Mike G]

Yep, well spotted, Terry.........but I knew you would The workshop had studs at 600 centres and few if any noggins. The house has studs at 400 centres, noggins at 1200 vertical centres, and there will be a solid board pressed up against the mineral wool. It should stay exactly where I put it.

 

[big soft moose]

Because it is 165mm thick, Pete, and there is no way you can achieve a good fit and persuade that thickness of Celotex into place: the friction is just too much. It's one or the other. If it were 100mm thick, then no problem.

fair point well presented - mine was two layers of 50mm ( i was working with a bunch of offcuts i got off of freecycle)

 

[StevieB]

Out of interest, why not use Celotex board in the walls too Mike - I thought it had better thermal qualities than the mineral wool stuff?

Steve

 

[Mike G]

Out of interest, why not use Celotex board in the walls too Mike - I thought it had better thermal qualities than the mineral wool stuff?

Steve

I will be. Keep watching

 

[AndyP]

Out of interest, why not use Celotex board in the walls too Mike - I thought it had better thermal qualities than the mineral wool stuff?

Steve

I asked myself the same question and came to the conclusion (perhaps stupidly) that because it is foil backed the Celotex cannot breath like mineral wall hence the air gap under the tiles in the roof. Am I wrong?

 

[TrimTheKing]

I'm guessing it's because there will also be a cavity between timber and blocks which will be filled with Celotex and the mineral wool is there to fill the timber cavity and provide extra thickness to the whole...?

Cheers
Mark

 

[PeterBassett]

It's going to be very nicely insulated at any rate!

 

[Mike G]

The gap between the blockwork inner skin and the timber frame will be fully filled with 100mm Celotex (except at plinth level, where another detail is necessary). Because Celotex isn't perfect (it's often curved/ bowed), and my timberwork and blockwork aren't perfect, I needed the insulation in the timber frame to give me a bit of tolerance. The mineral wool achieves this, filling any gap to the back of the Celotex. The net result will be a wall with a U value of just under 0.12, or an equivalent of having 300mm thickness of mineral wool.

 

[Mike G]

I should have posted this previously. This is the waste after foaming up the Celotex in the roof:



Today I insulated upstairs:





I spent rather a long time on the phone trying to organise deliveries etc, and I had a particular struggle getting the right wall ties for the next phase of the job. That will entail spending some more time on the internet tonight. I just found some time to squeeze in a bit of stud walling. This is the gable end of the small bedroom, and because that wall sits on the pair of glulam beams across the middle of the lounge ceiling, it can't have a blockwork inner skin as per the rest of the extension. Therefore, it will be a 320mm thick double-stud wall:



The stud feet overhangs the glulam beam by 20-odd mm, the thickness of a batten, because I have yet to bolt the two glulams together, and the bolt heads will stand proud. Doing it this way means they won't stick through the plasterboard:

 

[StevieB]

Impressive attention to detail Mike - I am pretty sure had I been ding this build I would have been scratching my head trying to work out how to hide bolt heads in a weeks time

Steve

 

[Rob]

wouldn't you just counterbore for the heads and sink them flush in normal circumstances? (With a hole diameter large enough to get a socket onto the head)

 

[Mike G]

I'm not supposed to this time, according to the structural engineer: the washers have to be the big plate washers, so it would mean carving out a 2 inch square about 30mm deep.

 

[Mike G]

I spent rather a long time at the builder's merchants first thing, getting stuff for the next week or two, so I only started on site late morning. First job was to finish the gable wall studwork. It is entirely non-loadbearing, so no lintel over the window opening:



I then cut and belted in (with glue) 4 bits of wood between the glulam beams. I will drill through the glulams at these locations, and bolt through the lot (this is all designed to take any possible twist under load out of the beams):



I filled the gaps between the glulams with insulation, which was an awful lot easier than I had feared. Then I did the second layer of insulation in the gable wall:



That's 200mm, so far. Then I started on the 3rd and final layer, but ran out of material. That's a nominal 300mm (12"):



A quickie of a job. I need a loft access hatch into the ceiling over the 4th bedroom. I decided to cut out a section of joist which was the same length as the timber required to trim the opening, so as not to waste wood. (Tight? Me?). Before:





After:



That will give me good access to the ventilation system which will be housed in that area.

The final job of the day was to make the bedroom wall between the 4th bedroom and the primary bedroom, at the back of the wardrobe. I can't make it in one go, because the floor is incomplete, and can't be finished until the blockwork is done, and I can't put the wall plate down before the floor. Note the triple-stud post supporting the ridge beam:

 

[Mike G]

The focus now moves back downstairs to the construction of the inner skin of the external walls. I took rather a while clearing a space around the walls, then cleaning the plastic sheeting and the cavity:



Whilst awaiting the delivery of some blocks and ballast, I loaded out the area with lightweight blocks. These will form the first 3 courses, before I swap to dense heavyweight blocks for the rest of the wall height:





Whilst still kicking my heals awaiting the delivery, I prepared the window openings for the arrival of the windows. Unfortunately, they were a day late leaving the factory, and so won't be delivered to me this week. Oh well, they are still ahead of schedule next week, as they were promised for the week after. Full details of those when they arrive, but in the meantime, would anyone care to hazard a guess as to the reason for the little diagonal piece of batten?



It wouldn't be fair to ask anyone to guess the reason for 4x1's alongside the window opening, so I'll explain that when the windows turn up.

Finally, my blocks and ballast arrived, so I could make up some lean-mix (1:8 cement/ ballast) concrete, and fill the cavity below floor level. Note that the top of this fill slopes away to the outside. The theory here is that if any moisture penetrates the outer skin it sits against the outer skin of the wall, rather than the inner. At door thresholds, the slope goes and the fill is flush to the top of the slab:

 

[RogerS]

Given that the diagonal brace is spaced out the same distance (1") at each end, I'd say it was a reference point against which to fit the windows as they are slid in from the inside.

 

[Mike G]

It's even more basic than that, Roger, although that is a useful secondary function.

 

[9fingers]

Is it to stop them falling outwards?

Bob