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The Essential Guide » Timber Frame | Sips » Heat Insulation and Sound Proofing For Timber Framed Houses

Heat Insulation and Sound Proofing for Timber Framed Self Build Houses.

Which is best for sound and heat insulation – Timber Frame or Traditional Build?

When people are considering the choices between Timber Frames and Traditional Build for their Self Build projects, two of the most important subjects tend to be “Sound Insulation” and “Heat Insulation”.

which best for heat and sound insulation. - timber frame or traditional?

With energy costs soaring and probably going to get more and more expensive, it’s very important to consider the day to day running costs of your new home, and for Self Builders, it is also usually one of the goals of the project to get a house that doesn’t transmit sound from room to room as if the walls and floors were made of paper!

The general thinking on this subject tends to be "Traditional Build" = solid construction / high heat Insulation / good sound insulation. - Whereas: Timber Frame Build = less solid / good heat insulation / poor sound insulation

I have been to many Self Build shows and spoken to thousands of potential Self Builders. – I often ask the question “Are you going to build “Traditional” or “Timber Frame”? – Many people give me a “knowing look” with a half smile and say “Traditional of course- we want a proper house!”

It is a myth that just won’t go away that Timber Frame is less of a “proper house” than traditional build. – In fact, from my experience, it is far easier to get a good solid, well sound and heat insulated house using Timber Frame than it is with a Traditional Build.

I’ll make a few comparisons so you can get an idea for yourselves of which may be the best choice for your project. – I’m not going to get technical because Building Regulations are constantly changing and I would have to keep updating this chapter to keep up! – The idea here is to give you a broad outline of how, in my opinion, the two constructions methods can give you what you are looking for in the way of heat and sound insulation.

Colour key:

Traditional Build:

Timber Frame:

Both about the same:

Main walls:

External skin:

Usually a Traditional Build will consist of a cavity wall, either with a brick external skin and flush or recessed pointing to the joints, - or a block outside skin with rendered finish.

Usually a Timber Frame Build will consist of a cavity wall, either with a brick external skin and flush or recessed pointing to the joints, - or a block outside skin with rendered finish.

Sound Insulation: Both of these options give the same levels of heat and sound insulation

Internal skin:

Usually a Traditional build will have a blockwork internal skin. There are choices between solid concrete blocks, or lightweight blocks which offer a higher level of heat insulation but cost significantly more than the solid blocks. – You can also increase the width of this internal skin of the wall from, say 100mm to 150mm to give further extra heat insulation whichever type of block you use, this will obviously increase the cost per block, probably by a little less than 50%. – However, the thicker blocks are 50% heavier than the thinner blocks, and you will usually pay considerably more per square meter to get the wall built. This is because there is more “labour content” involved, especially as the wall gets higher and the individual blocks have to be carried or hoisted to where they are needed.

Usually Timber Frame Build will have a Timber panel internal skin made up of either 4”(or for extra heat insulation 6” or even 8”) timber studs, attached to a “composite board” panel with a protective breathable membrane on the outside of the timber panel. The void created by the studs will be filled with insulation, usually fibreglass wool insulation, but for even higher levels of insulation you can use higher spec insulation products.

The cost of the panels themselves will increase between the 4” and the 8” options significantly, but the labour content is very similar whichever “thickness and insulation type” option you take, so the thicker, higher insulated panels will tend to be more cost effective and probably be able to offer more heat insulation than the equivalent traditional build option.

Between the 4” -8” option of wall thickness and the options for using upgraded types of insulation, it is generally easier and cheaper to get high levels of heat insulation in a timber frame than in traditional build.

Sound Insulation: In a detached house the sound transference to the outside is not usually a critical factor when it comes to making the choice between the two types of construction, but as a basic construction method, the solid concrete block wall will usually offer the best sound reduction qualities between the inside and the outside of the house.

Cavities:

Traditional Build and Timber framed buildings both usually have cavities in the external walls. – They can both be of similar widths and receive the same treatment with regards to insulation. – However, with timber framed buildings it would be rare to see a cavity with insulation in it. – It is cheaper and easier just to increase the spec of the frame itself than to add extra insulation later.

Internal walls:

Traditionally built houses tend to have 4” solid block walls downstairs and timber stud and / or solid block walls upstairs.

The solid walls will usually either receive 2 coats of plaster and a finishing “skim” coat either side of the wall, or a plasterboard finish which is fixed to the block with adhesive. – Depending on the type of plasterboards used, they can give better sound insulation than the solid plaster finish. – Boards also have the advantage of having a small cavity between the board and the solid wall, which not only helps with the sound and heat insulation, but also gives a “service route” for any wiring that may need installing at a later date.

The stud walls will be boarded with plasterboards and either “taped” or “skimmed” to finish. – The boards can be anything from 3/8” to ¾” tick and can be made from different types of materials which give differing sound and heat retaining qualities. – Commercial builders tend to use 3/8” boards with taped joints and paint straight onto the boards. – When I build, I tend to use 15mm “sound deadening” plasterboards to both sides of the wall. As well as being thicker, these boards are denser than standard boards, and give 2 advantages: they reduce sound transference between rooms and they give the finished house a more “solid” feel as you walk round it.

Some of the stud walls need to be insulated with fibreglass wool as part of Build Regulation requirements, but this insulation can easily and cheaply be added to all internal walls for increased sound insulation between rooms.

One weakness with the solid walls is that once they are built they are a lot more difficult to change or alter. Another weakness would be that to get solid walls upstairs you would generally need to have the upstairs walls directly above the downstairs wall so that the weight can be carried down to the foundations. – This restricts your layout options (steel beams can be used to support some of the upstairs walls but they can be a pain to get right, so are not one of my own preferred options!)

One weakness with the stud walls is that sound can pass through the joints between the plasterboards and the tops and bottoms of the boards. – You may think that these small gaps would not let a significant amount of noise through, but they can do, especially if the boards are not carefully cut at the top and bottom to form a tight joint with the ceilings and floors. - Another weakness would be the strength of the boards compared to the solid wall, but I don’t think I have ever encountered someone actually “breaking” a plasterboard wall by accident in a house! – If they did, it would not be a major task to change the board.

Timber framed houses tend to have all stud walls. – The spec for these walls will tend to be the same as for the stud walls in traditionally built houses. – They will therefore have all the same advantages and weaknesses.

Between floors:

Both Traditionally Built and Timber framed houses tend to have the same ground floor to first floor construction. I.E generally timber joists (or timber “I” beams”), with either chipboard flooring or traditional floor boards to the top and plasterboards to the underside.

Both types of construction can be upgraded both for sound and heat insulation in a similar manner:

1) Between the floors you can install the fibreglass wool insulation. – This will give improved soundproofing, and although not as important in this location, less heat transference between the floors.

2) You can upgrade the thickness of the floorboards. – The standard floorboard thickness is 18mm, by upgrading to 22mm you don’t add a great deal to either the purchase cost or the labour cost, but you get the benefit of the extra thickness for both sound and heat proofing.

3) You can upgrade the plasterboard the ceilings: Standard ceiling plasterboards will be 12.5mm thick. Upgrading to 15mm sound deadening plasterboard will help both sound and heat transference. – Hotels and hospitals sometimes double up boards to ceilings (and sometimes walls) to further improve the insulation qualities. – If you do the same, make sure you stagger the joints so that any sound getting through the first layer of board will hit a solid part of the board behind it.

4) You can install and “acoustic floor”. – There are various types of acoustic flooring types. – We’ll cover them later in this guide (if you need info before that chapter is written try a search on Acoustic flooring to see what companies there are near you and give them a ring to see what they offer).

Roofs:

Both traditionally and Timber Framed houses tend to use the same roof construction.

The main choice with roofing will be between “standard trusses” and “attic trusses” with the upstairs ceiling being of plasterboard.

Unless the roof is to be converted to living accommodation, insulation for wither timber frame or traditional build will take the same form. - Usually fibreglass. These days you generally need 12” (300mm) of this insulation to conform to regs. The best way to install this is to lay 3 layers of 100mm insulation, with each layer being installed at right angles to the previous layer. You can increase the depth of this insulation if you wish, but it the thicker it gets the less effective the extra depth becomes as a “cost to increased insulation” value.

If you are going to use the roof as living space, then to increase sound and heat insulation you can simply use a similar type of construction to that used “between floors”.

That pretty much covers the main parts of the building where timber frame construction can be directly compared to Traditional build in term of heat and sound insulation.

Conclusion:

For a significant proportion of the house, what you get in terms of sound and heat insulation with traditional build, you get with timber frame. For another significant proportion of the house, it is easier, quicker and cheaper to upgrade a timber frame to give you better insulation values than it is to upgrade a traditionally built house.

The major advantage to Self Builders with the timber frame option is that to upgrade anything, is usually only a question of “asking” for it to be done. – The designer will simply build the modifications into the design and then the frame will automatically come with all the upgrades included. – This could proof to be far less arduous than upgrading a traditional construction build, where every alteration to the standard design has to be dealt with individually, drawn, itemised, costed, found, ordered and delivered. – This is fine if you have experience of building houses, but when it’s all new to you, this extra work can prove to be quite a heavy extra burden when you are already sorting all the other aspects of the project out.

When it comes to “Traditional Build” versus “Timber Frame” for Self Builders, I would always recommend Timber Frame. – BUT there’s a new kid in town! – “SIPS” (Structurally Insulated Panel System).

If there is a possibility of something making it easier and better than Timber Frame for Self Builders, it could be SIPS.

Before you make your mind up which option is best for you, I would recommend reading the “SIPS” section of this guide.

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