Sustainable Roofing Retrofit Bristol - Finishing the floor/designing the roof steels. Week 7

This week consisted of finishing the floor structure, starting to build the purlin walls and some layout work.

Phil also set about rebuilding the gable wall, putting in 2 new lintels and sorting out the big rubble wall. This basically consisted of cracking off all the old cast concrete top and levelling it off with some new bricks/stone and pouring a new level concrete top for the flashing/copings to go on.

Felix and myself looked at the layouts and mapped out the colossal amount of steel going in to support the roof structure. It seemed a touch over-engineered but we were given a pack of drawings and its our job to deliver that so we went along with it. I then set about making a 3D model for both the steels and also to look at some of the junctions and details of the roof structure and external insulation.

Phil's gable rebuild.

The big rubble wall. I mentioned this in an earlier post but this wall is half the end of terrace wall and (a bit more than) half of a wall belonging to a house thats no longer there, I guess the people who demolished the big house felt it best to leave the whole wall there to buttress the end of terrace. It's almost a metre thick in places. It forms the parapet wall and therefore the valley gutter, it will have GRP over the wall and down into the gutter and either coping stones or cast concrete, with a gentle fall down into the valley gutter.

The floor structure in full swing. A lot of double and triple joists in this floor to carry various elements like the purlin walls, internal walls and also to trim the chimney stack and stairs.

Marking out the rafter intersection point on the front joists over the soffit. Its seems very far back because of the 145mm build up going on top of the rafters.

We stringed the rafter line to help map out for the steel structure.

The 3d model has been a really useful tool for helping to work things out and foresee some of the issues before they arise. I only modelled some of the structure just to help us look at some of the more complicated junctions and intersection points, I didn't bother putting in every single rafter. It was particularly helpful when looking at the insulation build ups and how they interact with the wall plates and facias - and of course the steels.

The roof steel structure! I won't name the engineers but I certainly won't be recommending them. It looks more akin to a skyscraper than a Victorian end of terrace. It was however still fun drawing them up and it will add a little complication in the construction.

I sent these off to the steel fabricators and that about wrapped up the week.