Passive House- The Sms Timber Frame System

Sms Timber Frame were approached with an enquiry, into whether or not we could provide a passive house using the Sms Timber Frame Eco System. Our answer was “yes we can”.

As you can see, this is no run of the mill design, the elegant, curved, Sedum roof is designed to blend in with the surrounding country side. Using a combination of engineered products we quickly got to work designing the structural shell without compromising the beauty of the curves.

Stage one

To create the “wave” like roof profile, we have employed 4 No. glu-laminated “Rib” beams which form the glu-lam portal frame, which in turn forms a true curved efect for the roof and the curved effect for the roof and the curved elevation. ( See the image below )

Stage 2

The roof infill structure is to be formed using 400mm deep Eco rafters at 40o centers. At 90 degrees to the “rib” beams (perpendicular) , this will be then sheathed/decked with WBP ply to take the roof covering system, because this is a Passive House, and as such, completely air tight, mechanical air movement is a requirement and the roof rafters (with their open pressed webs) provide a ready made service void to conceal the ducting without the need for aesthetically displeasing internal boxing.

The same system is employed for the first floor structure to accommodate service ducting in the floor structure . ( as shown in the image below ).

U Value = 0.1 w/m2kt (With timber cladding)

Sms Eco Frames ” Twin wall panel system” (above) effectively incorporates a thermal break in external studs which dramatically reduces cold bridging across studs / rails.
This is particularly effective where a single wall system with timber / render claddings are employed and not a standard cavity wall with a masonry skin.

The ” twin wall panel system” is designed to be stronger, lighter, more accurate, more thermally efficient, than solid timber studs. Using Kerto members (a structural grade ply) it can also be employed to form curved / profiled panels, as on this passive house project. (see image below)

 Sms Timber Frames’ twin wall system is designed so that a deeper panel system can be provided to give you the choice of insulations up to 350 mm.

Stage 3- Insulation

On this project we are using the ICYNENE insulation system because the product is sprayed on site and expands into every nook and cranny, it is ideal when air tightness is essential, especially on a curved structure where rigid insulation would be difficult to fit effectively.


More about Icynene

Icynene is a low density soft foam insulation, which is sprayed into/onto walls, crawl spaces, underside of roofs, attics and ceilings by Icynene Licensed installers. Sprayed as a liquid it expands to 100 times its own volume in seconds to create an extremely effective insulation and air barrier. Every crevice, crack, electrical box, plumbing run, duct and exterior penetration is effortlessly sealed to reduce energy-robbing random air leakage. Icynene adheres to the construction material and remains flexible so that the integrity of the envelope seal remains intact over time. The Icynene Insulation system has many health benefit. It keeps out pollen dusts, and also moisture meaning the risk of mould is minimized, creating a perfect environment for anyone who suffers from asthma or hay fever or any other respiratory illness.

Thank you for reading the introduction to this blog, please follow our blog to see the project take shape, with day-to-day updates on the erection process. It will have many images, videos, and insights as to how the work is carried out. Plus much more technical information, including air tight tests, thermal heat camera footage and hopefully a step frame video if the full build! Follow to see more.

Thomas Smith

Sms Timber Frame (Please feel free to email me at any time, i WILL respond )

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Sms Timber Frame- Posi Rafter.

Sms Timber Frame Posi-Rafters

Welcome to Sms Timber Frame. In this post we will be introducing you to our pre insulated, pre manufactured posi rafters. Another new addition to our family of eco products.

So what are Posi – Rafters?

Posi rafters are in general the same principal as a posi- joist, they are manufactured to various depths, and are made up of TR26 grade timber connected using the Steel webs. (See image below)

Advantage of the Posi- Rafters?

The posi rafter has many ways in which it can benefit both the energy efficiency and the build efficiency of your project.

  • The Posi rafters are pre-engineered and pre-manufacture before they reach site level. This saves time in installation but also saves time as profiles do not need to be cut for the rafters on site.
  • The Posi rafters can be face nailed, placed in a hanger or can simply be sat on a ledger attached to your ridge beam.
  • This product (as shown above) can be pre-insulated, this eliminates cold bridging through solid elements of your roof structure making your project more energy efficient.
  • Due to these joists providing a void through them, it is possible to run services, and soil pipes through your roof space. This void can be maximized to a depth of 210mm by using 304mm deep posi joists. This speeds up the first and second fix of your build.
  • The rafters have a larger service area to fix to, this helps to speed up both the tiling process but also the plastering process.

This new product can benefit your project phenominally. They are strong, economically efficient, easy to install, and when the speed of the build time is taken into account, cost effective. Please visit our website to see this product in a real life project that we carried out in Manchester. We completed the erection of the extension in 4 hours. using the Posi Rafter system. (Click Here)

Thank You for Reading.

Thomas Smith

Sms Timber Frame

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Sms Timber Frame Posi – Joists.

Sms Timber Frame now manufacture their own Pois-joists and price for these as standard to be included in every project we do. We are partnered with Miitek and take care of the engineering and manufacture of the posi’s our self with our specially designed press. Our floor structures, are engineered to be 50% stronger than is reqired by Building Regulations ( We don’t do squeaky floors ).

What are Posi-Joists and their advantages?

Posi-Joists are hollow joists where by a top and bottom chord are joined together using metal webs, they ARE stronger than standard solid joists and can there for span a greater distance which will  save money on timber and costly beam / steel support in some cases.

Posi-Joists can be used in both floor and roof structure, and can be manufactured in cassette form just as solid joists can.

Advantages Of Posi Joists

  • They are lightweight and can be top hung directly onto the timber frame panels, this speeds up the erection process.
  • They are manufactured by Sms Timber Frame to be ROBUST and are stronger than solid joists.
  • All of the Posi-Joists are pre-manufactured which adds to the off site manufacture process, this minimises time at site level.
  • Generally our posi joists are top hung, which minimises shrinkage and differential movement.
  • Minimum Posi-joists widths are 72mm as oppose to standard joists that are usually 44mm wide. This makes it easier for fixing the floor deck but also plasteboard finishes.
  • Services and ducting can be run through the Joists VERY easily, no drilling or notching is required speeding up site works, and omitting the need for boxing, duct work, and soil pipes.

Thank You for Reading.

Thomas Smith

Sms Timber Frame

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An Introduction To Sms Timber Frame

Sms Timber Frame, is a family run business, and have been operating in the timber frame industry for over 30 years and have acceptional experience on all timber frame projects. From our factory in Huddersfield, West Yorkshire, Sms Timber Frame produce timber frames to the HIGHEST of standards, through design and manufacture to ensure the site erection process runs more smoothly for the benefit of our clients and our erectors.

Sms Timber Frame is a family run business with a small but committed team, with many years experience in their fields. We encourage all of our team to take pride in all aspects of their work.

Sms Timber Frame of late have become more and more innovative with the products and panel systems we produce. We are now partnered with Miitek Industries and do produce Posi – Joists ( metal web joists ) for every project, and specify them as a standard feature of our timber frame structure.  We have also worked hard to produce a variety of different panel systems to allow  the customer to decide on the level and type of insulation for their project.  ( Please note all Sms Timber Frame Products will be covered in posts to follow).

Here at Sms Timber Frame we specialise in bespoke, domestic and one off projects. We are set up to deal with one of, bespoke new builds, domestic extensions and our speciality being first floor or “top hat” extensions. We carry out many of these project on a regular basis and have come across every situation and complication possible when carrying out such projects. Our wealth of experience means that we have a solution for everything that is buildable from a structural point of view.

Thank You for taking time to read our introduction, their will be more in detail blogs about the panel systems and products we offer and different types of products we use.

Kind Regards

Tom Smith

Sms Timber Frame

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