Building Internal Walls

Internal walls are often overlooked, but they’re an essential part of any self-build, says Mark Brinkley

Mark Brinkley explains why internal walls are an essential part of the building and shouldn’t be overlooked

Self-builders rarely think about how their internal walls should be built, and how the rooms inside are divided is something that is often left to the architect or the timber frame company to decide on. While every self-builder has more than enough decisions to make as it is, it’s worth at least considering the options.

Loadbearing or Not?

Internal walls – usually defined as room-dividing walls, as opposed to the insides of the external walls – come in two distinct flavours: loadbearing and non loadbearing. A loadbearing wall acts as a support for a roof, a floor, a beam or another wall above it. It needs to be a little stronger than a non loadbearing wall and, crucially, it needs extra support under it — usually an additional foundation trench.

In a new build, the structural issues will all be dealt with at the design stage and you shouldn’t have to pay too much

attention to whether a wall is loadbearing or not, but it can have a major effect on renovations, especially when you want to take down an existing wall. In these cases, it is vital to know whether or not the internal wall is loadbearing because if it is, then you will need to provide an alternative means of support. If in any doubt at all, then get the building professionally surveyed so that you know what you are dealing with.

If you are rearranging loads, then the building inspector will almost certainly want you to employ a structural engineer to design and approve the plan. The consequences of taking down a loadbearing wall without knowing what you are doing do not bear thinking about! In contrast, non loadbearing walls act as little more than room dividers and can be easily altered or even removed. Some Dutch designs for self-build shell apartments create large open spaces and allow for rooms to be customised out of partitions.

Stud or Blockwork?

Internal walls can be built up in a number of ways. In blockbuilt homes, the most common method is to use blockwork for the loadbearing walls, and timber studwork elsewhere. Typically, this translates as blockwork walls downstairs and timber studwork upstairs, especially if the roof is built using trusses, which usually transfer all the weight to the side walls. That’s not to say that studwork can’t be used for loadbearing walls – in timber-framed homes, timber stud walls are used everywhere – but using blockwork for loadbearing walls is almost always straightforward, whereas studwork requires a little bit more thought and possibly some doubling-up of uprights. The downside of using blockwork for internal walls is that it is so much heavier that it usually requires additional support below floor level. Loadbearing walls routinely require added support at their base, but simple timber partition walls can be built very simply off any floor without extra support.

Studwork doesn’t have to be timber. Many builders like to use steel channels, which are lightweight and very fast to erect, making it ideal for partition walls where loading isn’t an issue.

Soundproofing

Perhaps the main concern for self-builders when thinking about internal walls is the passage of sound. The soundproofing levels between rooms are governed by the Building Regulations (Part E2 in England and Wales, 5.2 in Scotland), which call for a minimum sound reduction of 40db (decibels) between rooms. This is not particularly onerous to achieve by using either of the main methods of construction. Blockwork walls will naturally achieve this level, but studwork walls require some additions in order to meet the standard. The key here is to pack acoustically enhanced wool insulation between the studwork and to use either 15mm or acoustic-grade plasterboard on the walls. This easily meets the 40db standard. You can add a second layer of plasterboard, or use heavier boarding to further enhance the soundproofing.

By and large, studwork walls are cheaper to build than blockwork: if you choose to upgrade the soundproofing in them, it will cost a little more but it will still probably be cheaper than using blockwork.

You can go to great lengths to soundproof your studwork bedroom walls, but a bedroom is only as soundproof as its weakest link and that’s usually the door. En suite bathrooms can be a problem as well because they are connected to the bedroom but exempt from Part E’s requirements for 40db sound reduction. It is easy to upgrade the specification in stud walls not covered by Part E to meet the same standard, and it is also relatively easy to improve on Part E’s requirements by using more or thicker plasterboard.

Wall Hangings

Another issue with timber-frame walls is that you have to plan ahead for items such as radiators, basins and mirrors. One approach is to install timbers (known as noggins) between the vertical studwork to carry the weight — simple enough if you know exactly where everything is going.

Alternatively, you can use loadbearing wall boards such as Fermacell or Habito at the plastering stage. These are much more expensive than standard plasterboard but you can fix heavy objects into them anywhere and they also act as good soundproofing. Lighter loads, such as pictures or wall hangings, can be easily dealt with by using plasterboard wall plugs. A good tip is to photograph every studwork wall before it is covered up as it can be difficult to locate studs afterwards. Some self-builders will even keep records of where the studs are located, but most rely on a studfinder, a specialised metal detector that picks out the nails or screws used to fix the boards to the studs. H