Underpinning for a loft conversion

When you come to sell, you might encounter a few problems selling, as soon as a buyer see the word 'Underpinning' they think of subsidence,etc.

 

We have undertaken many loft conversions and only ever had to do additional works to an internal wall foundation once. Generally underpinning is not the norm....by a long way. However every case is different and just because it isn't the norm, that does not mean to say that your property is ok without doing it.
Kiab is right, there is a stigma attached to underpinning. Wrongly in my opinion, but that is my opinion.
A loft conversion does add significant weight to the building especially if there is a bathroom, (Bath) installed as oposed to a shower. 1m3 of water = 1 tonne. Add to this the additional floor joists, boarding, insulation, plasterboard, plaster etc. Yes it is as significant amount of weight. Having a dormer rather than a hip extension, (Gable wall) might make a difference. However the gable wall section could be constructed out of timber framing and tile hung, which would be marginally lighter than a cavity wall construction.

Structural engineers do tend to over spec. these days, however I would too, as there are no prizes for failures and they are putting their reputation and insurance on the line. I would listen to the engineer.
If you are gutting the place and want to make preparation for a loft conversion later, you might be able to speak to your structural engineer about putting in a steel frame on the inside of the building which sits on its own pad foundations, bit like a protal frame. Worth discussing as this would mean that you don't have to worry about the stigma of underpinning.There is always a way around things, it depends on your pocket and..focus.

 

Now that is a good idea.

It's sad that underpinning has a stigma.

 

Way out of my comfort zone now.

Look at secondary steel frames for housesmight giveyou some ideas.

 

The steelwork will have to be designed by the structural engineer, will probably be a number of U/c's (Universal column) and beams.
If your engineer comes up with a design, the best thing to do is to approach a local steel fabricators, who will do all the necessary welding of plates and hole for bolt etc. It sounds complicated but it is very straight forward. A steel fabricator would probably be supply and fit all the steelwork as a package. There should be plenty of websites for steel fabricators on the web. Just try to get a local one. Try to use a smaller company, as you tend to get better service.
Take the engineers drawings into the fabricator and he will give you a price. Simple really.
Let me know how you get along.
Paul