Sustainable Roofing Retrofit Bristol - Traditional Victorian House. Week 1

I'm going to attempt to document all (most!) of the process of completely rebuilding this roof and putting it back with wood fibre insulation in a sympathetically done sustainable retrofit of a traditional building. I'll try to keep the posts up week by week, lets see how that goes...

The house is in the Cotham area of Bristol. It's a conservation area and therefore the roof must go back in the same manor it originally was, or at least visually from the outside. There will of course unfortunately be a lot of steel involved as modern engineers seem terrified of trying to actually accurately engineer anything but prefer to drastically over engineer everything.

There will be 4 steels in the floor. 2 steel ridges. A flitch beam steel ridge. 2 steel posts supporting the ridges. Madness.

The interesting part of this job, other than all the compound joinery and wonky angles everywhere! Is that we will be insulating with wood fibre, both between the rafters and above the rafters. We will up the rafters from 3" x 2" to 6" x 2", full filling them with flexible wood fibre. Then we will have a continuous unbroken envelope of 100mm rigid wood fibre on top of the whole roof followed by a breathable membrane, counter batten and tiling batten. The interesting challenge of this is we will have to bring in the rafter line to account for new build ups on top while maintaining all the angles and lines.

Roofs come in all shapes, sizes and conditions! This Victorian end of terrace in Bristol certainly has some interesting shapes...

By the time I arrived the guys had already stripped what we're calling the "outrigger" roof. Basically an extension onto the main house. It's not a very nice detail how they've jumped the ridge back up leaving a mini gable between the extension roof and the original roof.

For some unknown reason the outrigger roof is also of unequal pitch which really makes it look odd next to the tunnel roof connecting it to the main house.

A view down the ridge and hips shows some of the (unintended!) curves in the roof...

The first week involved lots of documenting. We set up a laser datum line across the scaffolding and marked in on lots of the poles and took measurements down from the various ridges so we could maintain our heights. We also took the pitches as best as we could but the rafters and hips were in some cases deflected by over 12 inches. This roof was close to falling down.

Whoever had fitted the skylight on the right of the above image had just removed the purlin presumably because it was inconveniently positioned! Many of the nail fixings were badly done of had completely rusted out or the timber had split and softened around them. Also the carpenters who built the roof had stubbornly refused to use any timber bigger then 3" x 2"... Even for the hips! The hips on this roof are around 7.5m long - and they're made from two pieces of 3x2 nailed together on edge...

We can see from some of the following photo's how it looked from inside. More scary than from outside!

The roof had been propped so many times over the years by various people and with various things, but all on to the 3" x 2" ceiling joists! Terrifyingly close to collapse.

First job was propping the whole floor over both levels from ground floor up. Then remove some weight off that roof!

End of a good first week. Lots of documenting of the original roof. I'll leave it with the last picture of the week I took and a classic of this roof structure... A great pic showing just how much the ridge had dropped, around 135mm over 600mm. Also showing the double 3x2 hips and the tripled up and nailed together 3x2 ridge!

They didn't make everything better back in the day.