More on lintels and cills

In between getting our Suffolk house in good order, to sell, we are still looking around for Steading lintels and cills.

Finding reclaimed granite is tricky unless you live somewhere close to where it is sold. Decent sized pieces occasionally appear on Gumtree and eBay but invariably need the buyer to collect. It looks as though it would take years to amass material for our 21 openings, plus an out-size one for the garage door.

New granite lintels
So we looked for new granite. We found a few places online and after a good deal of effort, filtered them down to ones we thought were serious. I tended to not bother with the ones that mostly sell granite worktops, so I came across Caledonian Stone and thought no more of them. I found a place on eBay that sold new kerbstones that might have done for cills, but were on the thin side. We discovered Lantoom Quarry, Liskeard, Cornwall. They have a good range of split-face lintels in three different colours and they publish their prices. Ric had bought from them and trusted them, but we wondered whether there was somewhere with similar prices but more local. We were not making much headway, so I revisited some of the earlier prospects. I looked again at Caledonian Stone and was surprised that they are based in Peterhead, just up the road from us.

They have a smartish website with a chat feature, I gave it a go and got contact details for someone who could give us technical information. He replied quickly, they do indeed do 2500mm and 3000mm lintels in grey granite. They are 290mm x 100mm profile in a range of finishes. They are priced between £250 and £300 each + VAT. I worked out that we would need 18 lintels (excluding one for the garage door,) the bill would be over £4,500.

I checked back with Lantoom and was almost shocked to find that 2100mm and 2400mm lintels were between £50 – £65 + VAT. We would need 21 lintels excluding one for the garage door, the bill would be no more than £1,400. Ric checked directly with the quarry on delivery costs. The lintels would weigh about 4 tonnes and cost £400-£600 + VAT to transport. Still around £2,000 for the lot, less than half the price of the local supplier. We might look at Caledonian Stone for their 3000mm x 290mm x 100mm lintel, for the garage.

The good news is that the lintels are stock items, we can order them once we are at the steading in April.

The garage door lintel
Which led us to ponder on how we would incorporate such a long lintel into the gable-end wall, without damaging it and risking the wall above not being supported properly. Suppliers are reluctant to give safe loading data, which is probably very variable for what is, after all, a natural product. After a quick Google, we found a simple calculation to estimate breaking load for stone lintels:

Breaking load = 2 x breadth x depth x depth x modulus(of granite) / length

They conveniently gave a modulus value for granite. We had to convert to Imperial units and convert the answer back to Kg – the breaking load would be approx. 5900kg. The same website gave us a working assumption that the safe static load would be 1/6th of the breaking load, approx. 980kg.

This is nowhere near enough on its own, however we looked last September at a Catnic box beam with supporting shelf, which, with a second one behind it supporting the concrete blocks, would easily be strong enough. The downside being that we would see the supporting shelf from below. Lantoom quarry suggested that the granite lintel could be self-supporting i.e. placed directly on padstones on the wall either side. We would place a Catnic directly above the lintel and push mortar in the gap between them. The Catnic would bear the weight of the wall above.

Ric suggested DPC between lintel and Catnic, then lifted up behind a couple of courses onto the inner leaf of blockwork. Any water that ran down within the wall would run out over the edge of the lintel, not behind it.

Cills
I am following a prospect for reclaimed granite kerbing to use as cills, but am not getting much of a response. We will give it a bit longer, then look at what Lantoom Quarry have. Ric suggests getting cills that are 50mm wider than the window openings and lintels that are 300mm wider. This would give us more scope for cutting longer pieces of granite in two, reducing costs significantly. He is asking Lantoom Quarry about 300mm x 150mm profile granite to see if that would be suitable.

Splitting Granite Boulders

2018 for us is looking like 2 weeks at the steading in the second half of April, a week in July for Andy only, 2 weeks in September and a week over Christmas. We are slowly cranking back up into planning mode. Ric is likely to be working up there over April & May.

One early job is going to be splitting our larger granite boulders to make them shallow enough to build into the outer skin of our new walling. Sawing is not practical, we will use the old fashioned technique of drilling a line of holes along the splitting line, inserting two metal semi-cylindrical pieces of metal in each hole, then knocking a steel wedge down between them, pushing them outwards. If this is done in steps with a break of a few minutes between each step, the boulder should split cleanly apart.

The metal work, according to Wikipedia, is known variously as plug and feather, plugs and wedges, feather and wedges, wedges and shims, pins and feathers and feather and tare. Ric has a set of them for 3/4″ holes (18mm).

Originally in the UK, the holes were made by bouncing an iron bar up and down – percussive drilling. We will use a suitably chunky rotary hammer drill, which will be our contribution to the exercise. The ones we looked at ranged in price between £600 (Bosch) and £1,200 (Hilti); a bit much for us. Ric suggested looking for unused older models, or second hand. So I discovered the Makita 4001c, readily available on eBay for around £400, the newer model is the 4013c at £670.

I bought the very cheapest one, advertised for £335. This was a bit too cheap to be real but having used PayPal, I expected that I would, at worst, get my money back. It did not appear by due date, I left a message politely asking when i could expect to get it. I was surprised to get a message back saying they were working away and would send it when they got back home. Even more surprising was the seller then cancelling the order and giving me my money back, because he would not be back in a sensible time to post the drill.

The new Makita 4001c rotary drill – not the current model, but then it is only a bit over half the cost of the 4013c!

So I went back to eBay and went for the next cheapest, £396. It looked less risky and was indeed despatched the following day and is now in our possession. It is the same general size and weight as Ric’s ailing medium breaker, one of our most useful tools so far. The drill has two modes, hammer-only and hammer/drill. In hammer-only mode, I expect it would be a good substitute for the breaker. I would try it out somewhere on our Suffolk home, but there really is nothing I want drilled or broken! We will find out what it is capable of in a couple of months.

I have bought two cheap (£10 or so) 18mm, 4-blade, drill bits. Also two spare pairs of carbon brushes, since they have a rated life of around 8 working hours!

As an aside, I learnt recently that one can buy SDS Max spade attachments, usually with a 110mm wide spade end. I reckon this would have been really useful whilst we were hand-digging foundations. Next time, perhaps.

Practising Drywalling

We are slowly but surely getting our house in Suffolk to a point where we can sell it. The most problematic bit had been a short length of corridor between two of the bedrooms – for as many years as I can remember, one side has been crumbly old lime plaster, the other side unfinished drywall on a stud partition. Factor in the ugly, tatty carpet and dodgy looking stains on the ceiling, and we had a minor challenge on our hands.

After a good deal of thought, we decided to strip much of it out and start again. I saw an opportunity to practice a small amount of drywalling and to really work on doing it properly. I am pretty rubbish at wet plastering and have fretted off and on about maybe having to get a professional in to sort out our hundreds of square metres of plaster boarding – when it becomes an issue.

About Drywalling
In England it is still common for plasterboard to be given a skim coat of finishing plaster. We are talking Scotland, so dry walling is taped and jointed, but not skimmed. The joints between boards must be filled and finished cleanly enough so the surface can be painted. Professionals use taping and jointing machines, originally perfected by a company called Ames, so practitioners are often called ‘Ames tapers’. The machines work in stages, firstly laying the tape that seals the gap between boards, with the first layer of jointing compound, then using progressively wider heads to build the jointing compound up to board level. They have rollers and knives that remove surplus jointing compound as the machine head runs up the wall. I aimed to do the equivalent job by hand.

Step 1 – The Studwork
I removed the existing off-cuts of plasterboard from the studwork and pulled out the left over clout nails.

The studwork did not have studs spaced correctly to allow a whole sheet of plasterboard (1200mm wide) to be fixed at both edges. This was easy to fix by adding one new stud. Even better it was a short one, above the doorway in that wall. I screwed the stud in place, at the steading I would probably be using the nail gun.

Step 2 – The Plasterboard
Having acquired three sheets of 12.5mm x 2400 x 1200 bevel-edged board and a box of 1000 35mm bugle-headed drywall screws, I cut the boards to size. I fixed the three sections of board with screws spaced at 20 cm intervals, down the studs and across the noggins. The screws were never less than 10mm in from the edges of the boards.

I had two problems that I need to work on 1) driving the screws in absolutely perpendicular to the board surface and 2) getting the screw heads to countersink below the surface of the board, without breaking the plaster. So I ended up with a few that were slightly wonky and one or two that were not below the level of the boards – these were a pain throughout. A valuable tip is to use a drill/driver and not an impact driver, which is just too brutal on the board. I have since come across drywall screw adaptors which are self-limiting, which I will get as a priority – they have a Philips #2 bit which disengages when the screw is just below the surface of the plasterboard.

Step 3 – Jointing
Next I broke open my bag of GTEC jointing compound and mixed batches in an old litter bin, using my drill mixer attachment. It behaved very well, forming into a perfectly smooth slurry, I can see exactly why in the US it is called mud. The 5kg bag I bought would have done about 5 times the area of board I was sorting out – it really is quite economical.

I used a self-adhesive 50mm mesh tape across the board joints, not the paper tape used by the machines – this was because I happened to have a roll of it kicking around. I am not convinced it makes any difference, I expect the paper is cheaper, but again, a little goes a long way.

With the tape in place, I used a three-inch wallpaper scraper to press jointing compound into the tape, I should have got myself a proper jointing knife but the scraper worked well enough. And the compound was very well behaved, easily forming a smooth flat surface into the bevelled edges of the boards. Any surplus that was squeezed out the sides was easy to lift off and re-use.

After the compound had hardened, but not dried out, I used a 6-inch knife to lay compound on top of the first layer. Again I pressed the compound right into the bevels on the board edges and, as long as I made unhurried single movements, got impeccably smooth finishes. I let it go off properly and used a plasterers flexible hand sanding pad to smooth off the imperfections, mostly at the top and bottom edges and where I had gone from smoothing down from the top edge to smoothing up from the bottom edge. A caution here, I did overdo some of the sanding and roughened the surface of the paper on the board. It is hard to recover from this and it did show through at the finish, even after priming – be sparing with the sanding block. In this case it did not matter because I was papering over the finished board, rather than painting.

For the third and final layer, I used my 12-inch float. I had let the previous layer dry out so I used a plant sprayer to dampen it. Again, provided I made smooth, single movements, I got a very good finish. This layer filled the bevels and brought the compound up to the level of the board. With minimal reworking, I achieved a very good join, so that after a light sanding, I achieved the required standard – I could run my fingers across without feeling any change in level. Mostly, that is: I made the mistake of correcting one defect after the compound had started to go off and made it all much worse. I would have had a slightly easier time if I had had a 14-inch float in place of my 12-inch one, it would have overlapped the width of the bevels by more.

And the wonky screws heads came back to bite me – I had to sand the heads down as best i could, it was not possible to completely disguise them without removing them and starting again.

Step 4 – Finishing
Once I had got the jointing sorted, I treated the whole area with primer. The proper drywall primer comes in 6 litre tins which would have been ridiculous for the few square metres I was working, so I got away with left-over paint primer. It should allow a future owner to easily remove the wallpaper we planned to paste over.

The Outcome
All-in-all, I felt quite smug with myself, for a job well done. I am slow, but am now reasonably confident that we will save a chunk of money and do our own taping and jointing, to a standard where we can paint the finished surface. I did not have to deal with either inwards-facing or outwards-facing corners.

Not much to see here, this is after priming, with no sign of the jointing showing through…

Top Tips

The right tools & materials are essential, in my mind. I would not have got good results without the bevel-edged board, the jointing compound, the mixer attachment for my drill, the three widths of jointing knives/floats and the plasterers sanding block.

Good lighting is really important. I started out working in a gloomy area and once I had lighting in place, I found it much easier to spot imperfections and do something about them.

The jointing comound, the mixerand the three-inch scraper/knife

Drill/driver, impact driver, 12″ float, sanding block and mesh tape.