One of the jobs that has been progressing (slowly) and has now just completed is the installation of the roof-line products: fascias, barge-boards, soffits and gutters. I think I may have covered off what we were looking to do in a previous blog entry but to re-cap, all these items are in high-quality powder-coated aluminium. The aim has always been to minimise the amount of maintenance that is needed on the outside of the house and going for aluminium finishes rather painted wood really helps with this, despite the much higher cost.
Now it’s up I’m really happy with it, with one exception which may actually prove not to be an issue when other trades have done their bit – more on this later. The finish is superb and hopefully this is starting to show in the photos.
The exterior of the house will be a mixture of render, western red cedar cladding and slate slips. On the photos of the exterior, anywhere you see blockwork that will be covered in the slate. The areas covered by the blue membrane will be mostly render, but the left side (looking from the front) at first floor level will be timber – this will also wrap around to the windows front and back. Before this works can be done though we need to get some aluminium strips fitted above all the large windows and these in turn require that the soffits be fitted.
Soffits ready for installation
Soffits showing ventilation strip
The soffits are held in place by aluminium white-headed rivets into a 50mm J-trim that is fastened to the walls. The render will be applied to carrier board that is affixed to 50mm battens, so when the rendering is complete these rivets will be hidden from view. The exception to this is above the large windows where we will have some alumium trims fitted as these trims will sit much closer to the wall, giving a (hopefully) nice detail between the trim and the render. The problem here then is that all those rivets would be visible. The reality is that they’d hardly be noticable from the ground but I was led to believe there would be nothing on show so there needed to be a fix. This ‘fix’ has been to fit another trim over the J-trim, hiding the rivets although a couple will be visible, but that’s all. This is ok, but close up you can tell there are 2 trims and I’m not realy that happy with it. The scaffold is in the way at the moment so I can’t tell if it’ll really be a problem or not. Either way I’m going to have to live with it.
The join won’t be visible when the rendering is complete
Just checked – it’s not visible from the ground
There were a few ‘disappointments’ along the way. First up was we only had the guys on site for a couple of days before they disappeared for over a week. I’ve still no idea why this was allowed to happen and there was no real explanation. Tied in with this was that we seemed to have a constantly changing work-force with what can best be described as a ‘mix of abilities’. One area that this really manifested itself was that they had started to use stainless screws to fasten the alumium. Aside from the fact that these screws: looked terrible, weren’t screwed in square and were silver so stuck out like a sore thumb, they hadn’t considered the effect of galvanic corrosion, which is shocking given that they work with aluminium every day.
Galvanic corrosion, also called bi-metallic corrosion, is a process whereby one metal corrodes preferentially to another when both metals are in electrical contact in the presence of an electrolyte. This is the process in play for a basic battery. In our situation we are looking at aluminium and steel in the presence of water, which leads to agressive corrosion of the aluminium! Some might believe that because the area of contact between the steel and aluminium is small then the effect would be negligible but in fact it is aggravated. There’s lots of information out there, but this page from Wikipedia is a good overview: https://en.wikipedia.org/wiki/Galvanic_corrosion.
So how do you prevent it? Easy, either insulate the two matals and stop them coming into contact, remove the electrolyte (water) or more simply don’t use dissimilar metals! Obvioulsy we went for the latter so all the screws had to come out and be replaced with rivets. I still can’t believe it was left to me to pick up. ‘O’ level chemistry saves the day again 😀
Ideally we would have fitted galvanised steel gutters, but there were two factors that led us away from this. Firstly, there was the galvanic corrosion issue but secondly I didn’t want to have to deal with yet another supplier, so the only real option was to go with alumium gutters and downspouts. The product itself is superb – very well made and sturdy but we needed to pick a colour, which isn’t easy without seeing samples. In the end we went with a satin finish metallic silver in RAL 9022. This was picked largely blind with only an internet photo of a set of re-finished BMW alloy wheels for reference. As it turns out, the colour is exactly what we were looking for. Relief!
Gutters look more metallic in the flesh
Temporary rain bag
The downspouts won’t be fixed until the exterior is finished so in the meantime we have polythene bags draped down the house. I can’t see these lasting a couple of months so I’m going to have to find a temporary solution I think.
A bit of wind
One final thing… We had a few days of high winds recently which led to one of the ridge tiles coming loose. Although this might sound bad it was probably to be expected as we haven’t yet fitted the ridge end caps.
The ridge tiles are secured using a dry ridge system, essentially screws and plates, rather than the traditional (rubbish) sand and cement method. This is not only quick to install but it is very reliable. The last ridge tile though requires an end cap to ensure that any wind doesn’t lift it up but most of those available are plastic and designed for different roof pitches. I’m still waiting on some aluminium ones to be delivered but I wanted to be sure that no matter what, the ridge wouldn’t come off. So, up I went and drilled another hole near the end and fitted a suitable fixing…
There’s a gap that needs filling
Additional fixing installed