Wednesday, 8 April 2015

Of posts, beams and 'wonky' walls

One of the things I am enjoying most about this stage of the renovation process (apart from the beautiful exposed brick walls that are seriously tempting me to turn the main floor into a trendy neighbourhood coffee shop) is the science bit. Learning about how a building (and our building, in particular) is made, what it takes to dissect it and the science behind how we go about transforming it into the space we want. The first big lesson I have learned is about posts and beams. The structural challenge of our renovation is going to be the retro-fit of a big beam. In order to open up the ground floor so that we can enjoy unobstructed views out of the back, we need to remove some load bearing walls and fit some steel beams to carry the weight of the upper two storeys of the house.

It sounds pretty straight forward and the science of it makes sense but there are two issues that arise: one structural and the other logistical. The re-design of the main floor calls for a beam that will run the width of the house - almost 21 feet. The bigger the load, the heavier the beam has to be - in our case, about 750 kg. To carry the two floors above. That's a big beam but it can be manufactured and delivered, no problem.

The logistical issue is getting the beam into the house and then fitting it onto its bearings, whilst at the same time supporting the load (the upper two floors of the house), having removed the load bearing walls. This is the bit that has kept us all awake at night.

Unlike with a new build, where the big beams are fitted and then loaded. Retro-fitting a beam into an old house means keeping the load from collapsing and then fitting the beam. Not only does the load have to be 'shored up' during the fit but the beam has to be manoeuvred through the existing building, through the front door, between the studs, out through windows and back into place.

With the majority of the demolition work now complete, the 'big beam' is the next big step for us. And whilst all the consultations and site visits were taking place so that the logistics could be figured out, we hit our first bump in the road...the wonky wall!

I've mentioned before how this house has already seen a number of renovations and bits have been added and built out over the years. The major previous addition runs over the main floor and the second floor and we have discovered that one of these large walls is 'wonky'. That is, in builder speak, it is not 'plumb'.

Our problem is therefore that if we have to install a beam to carry the load being carried by a wonky wall, then we have to fit a wonky beam. And if we build out and extend the wonky wall by another 8 feet, then we will have a wonkier wall. A discrepancy from the plumbline that is now at 4 inches, will be increased to 8 inches and that, when all is said and done, will not be a pretty sight.

The solution, inevitably, is to tear down the previous addition. Take out the wonky wall and rebuild it. This time, however, we will build it in wood rather than double layers of brick.  

And the silver lining to the wonky wall cloud? The new wooden structure will be lighter than its poorly built brick predecessor - the supporting beam will not have to be as heavy and it can be fitted before it is loaded, i.e. the old walls are rebuilt. And so, there is more demolition to be done and the budget will have to be stretched slightly, new drawings will have to go in to the city for the revision to be approved and our walls will all be plumb.

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