Slow going - my double storey extension build

[kingandy2nd]

This picture the following day and gives a view form the other angle of these steels in place:

Moving on from the rear, we had to repeat the process of lifting and shifting for the two 254 x 146 RSJs for the front wall, but this was less of a problem because the kitchen/garage wall wasn't in the way so there was too much manoeuvring around that was needed. In fact, they went in so quickly I didn't take any pictures of them going in!

The final RSJ was the one for the garage door and was another beast due to the steel plate on it!

I'd made another mistake at this point by failing to tell my SE that the existing garage pier was only 1 brick (215mm) wide and not 300mm as per the new side. That mean the steel would plate would be too big and I wouldn't be able to accommodate the 100mm cavity that I'd planned for the brickwork on top. Following speaking to the SE it was decided that we'd simply narrow the cavity space to resolve this issue...but that meant me cutting 40mm off 5.2m of 8mm steel.

1.5 hours and 5 x 9" cutting discs later I'd lopped off the extra plate and the RSJ was ready to go in.

Even though this final lift was arguably the easiest to do, the beam seemed really heavy and again it was a real fight to get it in at the right position with good bearing on both ends.

I think the above is the only picture I took of the whole genie lift. Barring the lack of manoeuvrability it was made the actual process of lifting very easy. The thing itself was ruddy heavy (and massive) when assembled, so you do need a bit of space if you're going to use one of these. Here's a screenshot/details of the model:

At this point the weekend was over, and the genie lift had to be returned to the hire company, but it wasn't the end of the RSJ story.

I kept looking at the beam over the garage door opening and it just didn't look quite right to me. Despite having levelled it at the time, something must have happened because it turn out to be quite out of level.

Not wanting to drop another £200 to hire the genie lift again, I did a proper cowboy job with my scaffold tower and 2 x 2 ton hydraulic vehicle jacks. Again, I didn't get too many pictures of this sketch procedure, but basically I had the missus raise the jacks a little bit at a time as I increase the heights of the acros. No only was I able to level up the beam, I also increase the height a bit to accommodate a garage door that I picked up second hand... more on that in a future post.

It wasn't the safest way to to it, but needs must and I was keen to crack on.

So the steels were £1.7k, the hire of the genie lift was £200 and I spent a couple of hundred more on bits and bobs (bolts, steel paint, cutting discs, etc). Therefore, total spend to this point was £25.5k.

Cheers
Andy

 

[mic2876uk]

Looks very impressive, not sure i'd have the confidence to be fitting a steel into an existing wall to make a new opening... I'd be far too worried about the house falling down!

 

[kingandy2nd]

Looks very impressive, not sure i'd have the confidence to be fitting a steel into an existing wall to make a new opening... I'd be far too worried about the house falling down!

Thanks. Yeah, it's probably he most nervy part of the whole build to be honest. I'd had some prior experience cutting a hole in the other side of the house for the double doors into the conservatory, so I kind of knew what to do...although this was on a much much bigger scale!

 

[kingandy2nd]

Sorry, I've lost a lot of ooomf with completing this thread, but the building has been carrying on. As has been all the way through this build, work has been crazy busy with long hours which means that the work has been confined to the weekends only...with seriously elongates the project!

One the steels were in, the next job was getting the joists in for the first floor. I opted for posi joists because of the 5.1m spans, with a ledger board secured to the existing house wall and then having the joists built into the new wall on the other side. I actually found with just sending plans out to a variety of suppliers for quotes meant I got a range of designs and sizes of posi joists selected.

In the end I went for 147 x 47 mm joists, which were 225mm deep (as I thought this would be better for me having the joists the same depth as a course of blocks - turns out it didn't matter, because to get the heights right for the floor I was not in line with my courses of blocks anyway!) I could have gone for 97mm wide joists, but there was only about a hundred quid's price difference to increase the width and thus reduce the risk of deflection.

I ended up going with a local firm, and 3 weeks later they all arrived along with the Eager 22mm floor boards which are glued and screwed to be part of the floor structure.

Ledger boards on and bolted in with M12 200mm coach bolts. I seemed to have a little more gap that expected for the joists, so I trimmed 3mm off each before lifting them all into place.

A small tip is to get all the joists up on one side, then run the supporting wood through the centres before then putting the joists into their final positions.

The posi joists aren't that heavy, but definitely a two person job getting them into position. You can see the central support wood (don't know official name) running down the centre).

Also noggins fitted to each end to prevent twisting/sideways movement. My labourer is always good with doing these sorts of tasks As you can see, I ended up with a course of single thermolite bricks to get the height of the floor right. As 3 courses of these equal one block height, I was able to bring the inner about outer courses back in line (for the wall ties) but laying a another two courses of these bricks above the posi joists.

As I knew my build was going to be very slow going, I opted not to fit the eager floorboards at this point. Although they have a protective coating, I was conscious that they could potentially be exposed to the elements for many months which would probably ruin them. However, I did want a proper platform to work from as I still didn't have a proper scaffold at this point.

Therefore I put a large tarp over the joists, then got 8 bits of 8 x 4 18mm OSB for a temporary floor. My other half stapled spare DPM over these OSB boards to give them some protection. For less that £200 it gave a decent platform to work from thought out the rest of the build until the roof was on, and allowed us to hold up high pretty much all the materials we needed for building the internal walls.

You can just about see in the picture above that the walls have been started. I did the upper floor connection properly with a channel cut with the disc cutter and a DPC inserted, with the wall starters then in place.

By this point (October 2020) the days were getting shorter, however a £40 flood light from Screwfix meant we could carry on into the evening, and make us even less popular with the neighbours

I had to take some chunks out of the original fascias/soffits/roof where the new walls were going to go, which was a but scary and then it was just a matter of cracking on with the walls.

The upstairs, but virtue of being a smaller room and having three windows was actually fairly quick to get built. Obviously by this point, the other half and I were also much happier/experienced in building so we could just work without too much planning/coordination.

However, as the walls were getting higher and higher, my temporary trestles / boards/ scaffold tower as a way of building was getting less and less safe. We made it this far without the scaffolding, but with the roof to do, etc it was time to call in the scaffolders...

I'm up to my photo limit again, but the spends on this bit were as follows:

Posi joists and floorboards £1,200
Temp floor and other misc bits and pieces £500 approx
First floor blocks £1,300 (I'd already bought all the insulation with the ground floor).

Total spend to this point £28.5k

 

[thomp1983]

You should be proper proud of all this mate, I'm labouring for the builder on our extension and it's hard going fitting it in with working full time and a young child and that's with someone who knows what there doing,

Your doing it all off your own bat and having to learn it all as you go and managing to make a good job of it too

 

[Mottie]

In the end I would like to get a little classic car to tinker with

I think I’ve seen that little classic car……

 

[kingandy2nd]

You should be proper proud of all this mate, I'm labouring for the builder on our extension and it's hard going fitting it in with working full time and a young child and that's with someone who knows what there doing,

Your doing it all off your own bat and having to learn it all as you go and managing to make a good job of it too

Thanks. YouTube is a god send for knowing what to do, but sometimes life would be quicker/easier if there was someone here that knew what they’re doing…so I think you’ve got it the right way round

I think I’ve seen that little classic car……

Ha yes, busted. This thread is about 9 months behind the real word

 

[mic2876uk]

I certainly don't miss block laying in october by work light. Looks good progress

 

[WoOt]

For the walls, which insulation did you go for and why?

 

[kingandy2nd]

For the walls, which insulation did you go for and why?

We went for ecotherm 50mm cavity wall insulation (PIR partial fill), basically because that’s what our designer spec’d when the plans were drawn up.

If I was doing it again, I’d not use it, I would go for full cavity fill with rock wool or similar. My reasons would be:

1. The PIR is a bit fiddly to get in (with the plastic holders on the wall ties.)
2. You have to be extra careful to not drop muck down the cavity as it obviously goes all the way the down.
3. I’m on my third torpedo spirit level, having lost two down the cavity and not been able to recover them

Cheers
Andy

 

[WoOt]

Thanks Andy, been following your build for a while and as I've started mine now (and saw it in your pictures) it felt like a good time to ask. Will take the advice and go for a full fill. Probably 100mm Knauf Earthwool.

 

[kingandy2nd]

Thanks Andy, been following your build for a while and as I've started mine now (and saw it in your pictures) it felt like a good time to ask. Will take the advice and go for a full fill. Probably 100mm Knauf Earthwool.

No worries. Will check out your thread

 

[kingandy2nd]

Time for another belated update

After calling quite a few scaffolding companies and having some wildly varied quotes, I found a company that would do the scaffolding all in for £1,950 with no time limit to the hire (which was a key thing for me being a DIYer as I was working slowly - most would only hire for 16 weeks and then charge extra). The price included going around the whole house once the extension was built in order that the whole place could be rendered.

With the first lift installed it was instantly so much easier to work on the blockwork - I kind of wished I'd got the scaffold up earlier rather than risking my neck, but hey ho.

We then cracked on with the walls at a pretty good pace (as the other half and I were getting into a good routine with the brick laying) and fairly soon the second lift of the scaffold was installed ready for the gable and the roof. You can also see in the picture below I started to cut into the existing facias, sofit, etc to allow the space for the new walls to go in.

At this point we're in mid-October and the weather hasn't been our friend very much. We don't like too far away from the sea and each year the Canadian Geese stop off at the beach near our house on their migration...which is always a sign of worse weather to come. Having the scaffold up made a great viewing platform one evening, so I thought I'd share:

With lintels for the windows installed and the gable wall built, we were now ready for the roof trusses to go on. (I forgot to take a picture with the wall plate on). You can also see that some of the mortar wasn't great on the inside of the clockwork where we got caught in a sudden downpour one day,

If you had eagle eyes above, you will have also noticed that I've removed a coupe of layers of tiles from the old roof. The next job was cutting all the existing roof trusses flush to the wall before the roof going on. I have a reciprocating saw, so this was a fairly quick and each job. I'd left some of the old felt in place hoping it might offer some weather protection to stop water getting into the cavity wall, but it didn't really. In hindsight I should have covered it over properly as the rainwater was running straight off the roof and into the wall for a week!

However, this was quite a milestone, with pretty much all the blockwork now done, we were progressing onto the roof!

BC came out for another visit at this point and signed everything off, so happy days!

After shopping around (again) I found one of the local companies was pretty competitive for the the roof trusses so I ordered with them and they were with me a week later. As with the posi joists, I just sent them my plans for the extension and they came back with all the calculations and lay out for the trusses, so it couldn't have been much easier!

And here they are:

Between me and my other half we were able to lift these up onto the scaffold without issue. We stacked them at the base of the building, I went up the scaffold with a rope which got tied onto each joist. My other half ensured each trust cleared the poles that were sticking out at 1st floor level as I lifted each truss up and over onto the top of the scaffold, where we stacked them ready for assembly. (Bit of a rubbish picture, sorry). I'm not sure this method would work for everyone, but as our roof is quite a low pitch, the trusses could be lifted by me alone.

The gable end went in first (which you build the blockwork up around later) and then the joists went in one by one in the method you can see below. We lifted them over the room and left them hanging upside-down, then we got them to the correct spacing and flipped them up and nailed the truss hanger in place (you can see a couple of them bottom left).

For the gable end we had fixed a bit of temporary wood in place (dark brown bit of skirting board), just to hold that in place, but the rest of the trusses went up using only the hangers until the wood bracing was fixed in at the end. You can also see the wall plate and the strapping to hold it down (rear wall). As the window in the front was over 2m wide, which is the max spacing for the strapping, I also added in some bolts which I resin'd into the blockwork to help hold the wall plate at the front). I had make a small booboo with the wall plate as I'd not notched it to join together, but BC were happy with the nailed plate to hold it together.

Time was pressing on a bit in the day, as you can see by the next photo, but within the day we had all the trusses on the main roof on.

Before we'd finished for the day I'd put some of the bracing on to hold the joists in place properly, but it was too dark to take a picture at that point in time. So here's on from the next day.

At this point I'd refrained from starting on the valley as this would mean breaking into the old roof and making the house really not water tight. It was mid-November by this point, so the weather wasn't great and I'd written off a couple of weekends to the weather already - I was therefore waiting for a few days of clear weather before attempting the next stage.

It's not a great shot above, but I'd cut in all the blockwork on the gable now and mortar'd the gable runner in place. I used some timber battens (red) which were resting on the scaffold and screwed to the gable runner to hold it level while the mortar dried.

At the picture limit again now, so I'll call time on this post here. Expenditure update at this point:

Scaffold £2k
Roof Trusses £600
I'd also treated myself to a precision nailer for all the metalwork (£300)

Total spend to this point £31.5k

 

[kingandy2nd]

Ok, so now it was the last weekend in November and it was time to do the thing I was dreading the most, breaking into the original roof and making the house not water tight. Well, I say that but the existing roof was already not in good shape with a few leaks and damp patches. As the extension roof would extend over about 25% of the original roof and the original roof was buggered, it made it a non-brainer to replace the whole roof at the same time...although this did add somewhat to the costs!

The roof pitch is quite low at 17.5 degrees, which limits tile choice, but in the end I went for like-for-like replacements of Marley Wessex tiles. However I changed from brown to grey colour. By this point we're already into month 7 of the CV19 pandemic and building supplies were a bit hard to come by. I have intended to use all Marley products (felt, dry valleys, etc) in order to benefit from their guarantee... but I simply couldn't get all the products from Marley so ended up with various suppliers of elements of the roof. No ideal, but in the end I was actually grateful to get my hands on the tiles (1,350 of them) because some places were quoting a 20 week lead time (I got them in 3 weeks in the end).

So back to creating the valley. Along with the roof trusses I got a valley kit made, so it was just a matter of pulling the tiles off the roof in preparation for getting them all erected. I used some string line to mark out where everything needed to go, and what tiles and battens needed to be removed.

It'd treated myself to another tool at this point, a Dewalt compact circular saw (DCS571) which was another great buy. It's perfect for cutting battens, and sheet materials. It was invaluable in making the battening on the roof quick and simple, but is also now my tool of choice for any such cutting. It'd bought all sorts of metal brackets to hold the valley kit in place, but actually just sticking some timber battens (pink) behind each valley truss and nailing those to the existing roof trusses was by fair the easiest way to do it. The bracing at the top was just temporary to get everything plumb.

You'll have noticed the valley support boards running up the sides to support the GRP dry valleys I was using. I was a bit stumped with how do do those, but I found a helpful previous thread by @noseall which gave all the details, which I just copied below (which is a picture made way though making) - basically just cuts of batten holding the 8 x 1 inch planks in place. The old timber battens were removed later.

Once both sides were lined with wood on the valleys, it was a matter of running the breathable membrane and then the GRP valleys. I actually fluffed to the top up, as I should have made the two valleys meet nicely at the top, but at the time I thought I would be applying some sort of flashing/capping to the top (as it would also meet the ridge of the existing roof here)...but it turns out there's no such product where the valley and the ridge meet at the same height.

Thankfully I had the off-cuts of the GRP valley (there's one on the right hand side near the top of the fitted valley), so I was able to fashion a suitable join later and have enough overlap down the valley for it not to be a problem.

Then came the fun part of running the membrane and battening it. https://www.fixmyroof.co.uk was really helpful for understanding the processed need and the spacing out, so I'd recommend using that site.

The photo below is quite busy as there were lots of offcuts left on the roof, and not all of the battens were fully fixed (especially at the joins) as I wanted to check my spacing calculations for the tiles were ok. I was using my 1st fix dewalt nail gun DCN692 (with 65mm galvanised nails) and my new mini circular saw, which made the battening pretty easy - most time is spent worrying about the spacing to get the right tile overlap.

It turns out my spacing was fine, but I'd made another mistake here which wasn't visible unless you look at the roof side on to the direction of the battens. From the front the battens looked bob on, and the spacings (31.5mm in my case) were fine. But a combination of the battens not being actually straight and the ends of the roof trusses (from where I was taking my measurements for the first batten placement) meant all the battens were wavy You really couldn't notice from looking at the roof front on, but at 90 degrees it was quite pronounced.

Therefore the whole side was removed (I was grateful I'd not nailed it all in). The membrane was discarded, which made it an expensive mistake (as it's £60 a role) and this took about 3/4 of a role. On the second attempt I ran a sting line from one end of the roof to the other and took my first batten measurements from that.

As you can see from the above, as a temporary measure I replace the tiles with some new membrane under it to try and keep the rain out (unfortunately we had light rain every day despite the forecast saying it would be dry), so this arrangement didn't last long. I started with the smallest section of the original roof and pulled all the old tiles and felt off the roof.

Although the old felt was gone, and there were a number of broken tiles, most tiles were salvaged. Across the whole roof there were about 750 ties that were whole, and after leaving 'Free' a sign outside most of them were taken by the neighbours as a lot of estate has the same tiles, and not many folks have replaced their roofs yet.

For the existing house we put in an extra 200mm of insulation role on top of the 200mm already there.

Then on with more battens on this bit of the roof. I think from the below, which as pre-removal of the wonky battens, you can notice some of the variations in the batten placement, which I then sorted out afterwards. You can also just about see at the top on the left the ridge brackets for the ridge.

And then onto the other side of the extension and the existing roof, and more of the same. Here's a nice sunset shot

It was quite a spendy month at the time, with everything from the roof (tiles, battens, membrane, valleys, clips & fixings) being supplied in one go at a cost of £4.5k.

Total spend to this point therefore was £36k (Including about £2k of costs for the existing re-roof).

 

[kingandy2nd]

So another (relatively quick) posting for me!

Following on from the above post, I'd notice the gable end ladder on the original roof was pretty rotten, so I had to remove that and replace it.

I didn't have the scaffold all around the house at this stage, but on the scaffold tower I was able to replace the offending timber. It will be hidden by the new fascias in the end, but I thought it best to change while I had the opportunity.

Now we had a water-tight roof - at least on the double storey part of the extension, we actually didn't have any way to get into the room other that climbing through the window openings!

Inside the new bedroom was the window that was on the existing landing, and the plan was always to convert the window into an opening to get into the new bedroom. Breaking out the Evolution disc cutter, the brickwork below the window was cut out - to the width of the planned opening. If you're wondering why I didn't open up the whole window as two parts:

1. The outer brickwork was cut to accommodate a temporary UPVC door I bought from eBay for £50 (in order to keep the house warm through the winter).
2. The inner blockwork was cut to the final width of the opening, leaving some blockwork in place where the stairs start to go down in the house.​

​

Getting the window out was more challenging than I expected. I always use a decorators pallet knife to pop the beading out to get to the glazing, which was fine, but 4 of the 6 fixings into the brickwork had either been rounded when fitting or were rusted in situ and the impact driver couldn't get them out. In the end I got my 9 inch angle grinder and went straight through the silicon and the fixings in order to get the window out.

The cracks you see in the blockwork are actually historical. I thought I'd made them, but on inspection from the inside there was actually scrim tape in the existing plaster (which had hidden then from the inside), so it must have been historical. I later on replaced the top block.

I failed to take a picture with the door fitted, but it looked a bit odd (brown upvc fitted backwards with a letter box!), but for £50 it's done it's job!!

Ok, so back to the roof!

We'd carefully removed the old tiles and stacked them around the scaffold as I knew they'd be useful for the neighbours. In order to get 400 tiles down, and then around 850 tiles up, we hired an 8m bumpa lift. We got the electric version, as this is much easier to reverse to take stuff off the roof - but it was an great bit of kit as I didn't fancy lugging all the tiles up and down the ladder.

It took a full day of grafting in shifting the tiles from where they were stored, then onto the bumpa and organised around the scaffold ready to go onto the roof.

Once the tiles were on the roof, the job of fitting them was quite straight forward. On the old roof, only the verge tiles were actually clipped in, and all the other tiles were interlocked. However, in line with current guidance, all tiles were fixed in, with double fixings around the edge.

The Wessex tiles I used had specific eves clips that also fill the gaps in ridges (to stop bird, insects, etc getting in), and then across the general roof I used these 'solo' clips. Picture here with one on top of the tile for display, and one fixed in place. These weren't too bad to use, but obviously it does add to the time it takes to fit the tiles.

Started on the shortest side to get practice in...

And then the other side done.

I made two mistakes at this stage. Firstly, I'd not fitted the fascias and soffits before putting the membrane on the roof. I should have done all this first, but ended up doing it afterwards as the tiles lean on the fascia - which made it all much more difficult to fit that it needed to be. Secondly, in my keeness to get the tile on the main body of the roof I chose not to cut the tiles for the valley section as I went. It wasn't the end of the world to do this afterwards, but it mean dismantling quite a bit of the newly tiled roof due to the way the tiles lay on the one below. So if doing again, it would be fascias and soffits first, then whole rows of tiles including cuts at the same time.

However, getting back to do the valley tile cuts, I used these tile C clips and the bottom of the tiles, and then these funky 'Kro' clips at that are hammered to the top of the tile, and then you put a nail into the batten above, wrap the wire around the nail and then hammer it home to hold the wire in place.

9 inch angle grinder made the cuts in the tiles easily, but definitely you need to measure thrice and cut once when it comes to getting all the angles nice against the dry valley.

I also made very good use of the damaged, cracked, etc tiles for the valley cuts.

And these getting fitted into place:

Spending update, extra clips C and kro clips, were about £50. Second hand door picked up locally £50. Bumpa hire was £150. Big expense, which I've not really mentioned was all the roof plastics - soffits, fascias, gutting, fixings etc. I'm doing the whole house and the soffits are all 450mm wide (which isn't cheap) - £1.8k for that.

Therefore total spend to date £38k (including about £2.8k for the existing roof).