How to Add Another Storey to a Bungalow
Project manager Oliver Steele-Perkins advises one reader on how to add another storey to their home
QQI’ve bought a bungalow with a view to renovate it and have been advised that converting the loft would be unfeasible (due to head height). As such, I hope to add a new storey to create the bedrooms I need. What do I need to consider and how much will it cost to add the extra storey?
As with any project, the starting point must be doing your research to check that the project is viable. And that means looking at all the planning issues involved, assessing your bungalow’s structural stability, judging whether the existing footprint will lend itself to a successful project, understanding the depth and shape of the existing foundations, and knowing whether the existing internal walls are loadbearing. Yes, lots to do — but all really important stuff.
where to start
Let’s assume you’ve already got floorplans to hand. I’d suggest you start by checking whether there are also any original construction drawings with your deeds. They are likely to show the depth and type of foundations, the drainage system and which internal walls have foundations, which will all be useful to your design team when they start working on the proposed design. On this project that we project managed (right and overleaf), the original plans were available, which helped immensely. You could also try searching out local building control records.
However, if you have no luck down either of those routes, you can consult a structural engineer. They should be able to advise you on ground conditions but will also likely recommend that you dig a couple of trial holes to measure the depth and record the type of foundations that are in place.
This involves digging holes large enough to expose the foundations of the building, around a metre in depth and width, so you can see what’s what, and also take a soil sample at the bottom of the pit. Bag up your soil sample, send it off to a laboratory for testing – just search online for a UKAS-accredited soil-testing lab – and then share the results with your structural engineer. Alternatively, you could appoint a geotechnical
consultant, who will liaise with your structural engineer to carry out the necessary work. Either way, the information gained from this survey will then enable your structural engineer to give you the right advice on ways forward, depending on whether the existing foundations are robust enough to support an additional floor.
thINk aBoUt tImBer Frame
On this project (shown above), we opted for a timber frame, as the load of a timber frame is far less than blockwork (masonry), and you might like to do the same. It should remove the need to strengthen or underpin the existing foundations, which is time-consuming and expensive.
The general cost of a timber-framed conversion project in the south east of England is approximately £1,800/m2, subject to fit-out specification.
If you go down the timber frame route, you can start the detailed design process as soon as you’re satisfied with the planning status. During detailed design, think about what materials you’d like to use; your architect will really help you here, and it’s important to work with planning conditions in mind — you may also need to provide samples to your local authority as a condition of any approval.
If you are thinking of using a prefabricated timber frame (which in my view is more efficient than a stick built route and allows you to package the work to specialists), use your planning application drawings to get a high-level budget estimate from timber frame supply and fit companies.
When it comes to preparing for the build stage, my advice is to start early: commit to a single contractor, then focus on all the other components of your build, so you can form a good scope of works. If you’re taking the self-build route, look at what other trade packages you’ll need to bring in, such as a new kitchen or bathroom.
other CoNsIDeratIoNs
l As part of the planning process, you might need to carry out a bat survey (see page 143 for more).
l I’d advise naming your timber frame supplier as a required supplier in the builders’ contract. This has several benefits, including cost control. It also means you’re asking your builder to take on some responsibility for the co-ordination and management of that supplier.
l You’ll need scaffolding, so ask your frame builder exactly what’s needed, making sure it dovetails with other aspects of the project, and keep your scaffolding company in the loop at all times.
l Consider whether you can sell any materials from the original bungalow; in the project shown left, we sold the roof tiles and the internal parquet flooring.
l Look into the ‘easi-joist’ system and consider using them instead of traditional joists. They make for quicker installation, and are great for first fix plumbing and electrics, as they allow cables and pipes to be routed almost anywhere without needing to notch, cut, drill or trim joists.