Jointing and finishing: walls

With the ventilation up and running. the last job was to fit the vent grilles into the ceiling. According to the supplier, these are simply pushed up into place - not a very good solution, as thanks to gravity, they just slip down to leave an unsightly gap all the way around. Here's the metal collar sliding away from the ceiling after fitting ...  

... and with the vent grille fitted, showing the unwanted gap to the ceiling.

Frustratingly, we have found this a lot in housebuilding, where things often seem to be designed with little thought as to how they will fit together with other materials (usually leaving builders to bodge something together using silicone/glue/crumpled-up crisp packets, etc). It wasn't possible to glue it in place as the grilles need to be removed for adjusting the airflow, so yet again we'd have to come up with our own fix.  

After much head-scratching, Alan came up with a possible solution... 

... he drilled small holes in the plasterboard and attached some thin bolts to modified spring toggles on the top side of the ceiling...

... then after cutting small slots in the metal collar, he was able to position it under the bolts and tighten them right up onto the ceiling. As the collar rose up, the spring toggles acted like a captive nut and were prevented from turning by the metal edges of the collar itself.  

Once the collar was flush with the ceiling, the vent grilles would at last sit tightly in place with no gaps. It worked well, but the fact we had to go to such lengths to get something done properly was ridiculous. 

With the ceilings done, we returned to finish the walls.

We'd previously filled all the gaps between the boards using Fermacell jointing compound but (as with the vent grilles) were left to figure out our own way to fill the larger gaps around the window reveals.

The jointing compound appeared to be holding up pretty well, so we decided to use that for the outside corners of the window reveals too. The ubiquitous spray-foam proved handy here as we pumped it into the gaps first. This would give us a solid surface to fill onto (as well as insulate and glue the reveals even more firmly into place).

The jointing compound had to be applied in several thin layers. With 27 windows to do, this meant many hours of work. Fermacell was not quite the simple-to-fit product that it had claimed to be...

Unlike plasterboard, you don't need to fit any metal beads to the outside corners. The Fermacell jointing compound is tough enough to use on its own, though does go off extremely quickly once mixed up, so has to be used fast.  

Many pro plasterers deride corner trowels, but with such a rapid-drying compound, we found they worked really well and after a little practice, we could produce sharp corners very easily and quickly. 

Once the corners had dried, we gently sanded them to a smooth finish.

As advised by Fermacell, we left a 5mm gap between the reveals and the window frame and filled this with decorator's caulk.

The aluminium window frames do expand and contract slightly, so the caulk acts as a flexible joint to reduce the prospect of any cracks developing.

It was a relief to get the reveals for the large feature window completed.

More compound being applied around the windows downstairs. In the kitchen... 

... and lounge.

A little research into caulk was revealing. Cracks often develop because caulk works best when it's filling shallow 'square' gaps rather than deep 'rectangular' ones (like the kind we had around our windows...) To help prevent any issues, we pushed foam backer rods into the gaps; these thin strips of foam act as a backstop for the caulk, 'square off' deep gaps and generally make the caulk less likely to fail in future.  

Once the foam backer rod was in place, we filled the gap with a big splodge of caulk...

... then ran a (wet) flexible plastic packer down the joint to get it level with the reveal. 

More gaps to be filled around the study window.

Using a packer worked well to create a smooth, level joint. Annoyingly, we found even the best quality caulk does tend to shrink back when completely dry, so getting a perfectly flat finish is a pain.

With the gaps filled around all the windows, the rooms were finally getting close to completion.

Final finishing of the wall surface was a thin application of Fermacell Fine Surface Treatment (FST). This is a lightweight filler that is pretty easy to apply; you spread it on thinly... 

... and trowel it down. The only problem is we had around 600 square meters of walls to do! 

It was during these long hours spent FST'ing that we wondered whether it was such a great idea not to use plasterboard. Fermacell is sold as a plastering-free solution, but it had proved to be one of the most time-consuming and arduous parts of the build.       

The electricians had proposed a rather inelegant solution to connect the shed power supply to the consumer unit, so we decided it was better to change things around a bit. The connection would now be made via a box outside, but that meant removing the thick, armoured cable and the only way that could be done was by cutting a hole in the wall. We did ask why they put it in there in the first place...

It left a bit of a mess, though one of the advantages of Fermacell is its strength and ease of repair.

Alan glued and screwed some strips of Fermacell inside the hole to act as a backing board...

... then glued and screwed some more pieces cut to size to fill the hole.

A few layers of Fermacell compound filled the gaps and after sanding and FST, you'd never know there had been a repair.

Once all the walls had been compounded, caulked, FST'ed, sanded (and we'd recovered from our nervous breakdowns) the rooms were finally ready for painting.

We will eventually be painting the rooms in a variety of colours, but used a white contract matt paint as a basic mist coat/primer.  

Freshly-plastered walls are extremely porous and tend to absorb so much moisture that normal paint can dry out too quickly and start peeling off. Applying a watery mist coat first, acts as a sealer and gives the topcoats a much better surface for adhesion.

With Fermacell it's slightly different; the FST is emulsion-based anyway, so tends to function rather like a mist coat and generally you can paint directly onto it. But our walls were looking pretty patchy, so a mist coat still made sense as it would help give us a clean, even surface for our topcoats.

Before...

... and after.

The white paint also helped show up any areas of the wall that still needed extra filling or sanding.

Halfway round the lounge.

It was strange seeing the whole house with a trendy (albeit temporary) all-white look. It's certainly much easier to paint than colours (no cutting in around the ceiling for a start) but for all its obvious brightness, it felt a little empty and flat.

Just adding a thin layer of paint to all the walls immediately made the place feel less like a building site and more like a home.