The Loft Specialists

Covering Manchester, Cheshire, Lancashire, West Yorkshire & London M25

Modern timber framed houses / trussed roofs

Watch the video of how timber framed houses are converted

How to convert the loft space on a modern timber framed and truss roof house

Question:- We have been told that due to the fact our house is a modern timber framed house we can not convert the loft area there. Is this correct?

Answer:- No that is not correct.

Question:- We have been told that it is very difficult and expensive to convert the loft space on our house due to the fact that it is a truss roof design. Is this correct?

Answer:- No that is not correct.

Typical design for most loft conversion projects.

Steel beam supports.

The most common design and the initial starting point for loft conversion supports is to install two or three steel beams, running parallel to each other spanning from either party wall to party wall (terraced properties) or from gable to gable (detached houses). These steel beams are resting at the ends onto a standard brick wall, either cavity construction or solid. The Architectural designer will initiate designs to show all floor loads and dormer loads (basically all loads created by the addition of the loft conversion) will rest onto these beams.

Timber framed houses

Timber framed houses are just that, houses built from timber frames with a skin of brickwork or even timber cladding wrapped around purely for the prevention of water and other weather penetrations. The internal and external walls consist of timber frames covered with plywood and plaster board then insulated between. This type of structure is excellent at spreading loads and redistributing pressures over large areas. However this type of structure can not support the bearing of large steel beams point loaded in specific locations.

I Beams

I beams are work shop manufactured timber beams that are extremely light in weight yet extremely strong. These beams span the full length of the house spanning from front to back resting on timber walls below just as the roof trusses do.

Question:- Why can the timber framed house support these I beams, but can not support steel beams (RSJ's)? 

Answer:- Because there are many timber I beams usually 2 per metre (approximately 10-15 on the standard size house) spread evenly across the house rather than 2 steel beams placed directly onto 4 point loads. Also the combined weight of 15 of these I beams would be fraction of 1 steel beam. We at TLS offer the above design features as standard throughout our product options at no extra cost.

Trussed roof houses

Question:- How do I know if my house has a trussed roof or not?

Answer:- This can be a little confusing and may not be easily identified, but we will try to show examples and give some basic advice on how to determine if your roof is a truss roof rather than a traditional design.

Firstly look at the image showing a cross section of a typical house.

Please look at the overall triangle shape, it is made up of two basic pieces (rafters) resting on the wall plate of the house, then connecting the triangle at the bottom are the bedroom ceiling joists. Quite often with the addition of purlin beams (larger timber beams placed midway through the length of the rafter).

Then compare this simple triangular design with that of a Truss ( a single unit of workshop connected timbers forming a pre designed triangle).

These trusses are manufactured in a workshop creating the pre formed triangle shape of the roof slopes and the flat section that will become the bedroom ceilings. These trusses are delivered to site on large trailers then crane lifted on to the house, quickly and easily bolted onto brick walls or timber frames of newly built houses, then covered with roofing felt and subsequently tiled.

To try to determine if your house has a truss roof or a traditional roof see if you can identify the intermediate pieces of the truss looking through your loft hatch (shown here) these would not be apparent on a traditional roof structure. We at TLS would be more than happy to identify this for you.

Question:- I have determined my roof is built from these pre formed trusses, the intermediate pieces of these trusses are in the way of where I would like the new loft room space to be, how can I remove these sections.

Answer:- This is an extremely difficult operation to plan and must be carried out with extreme caution as removal of even the smallest intermediate section of a truss can destabilise the whole truss and collapse the entire roof structure. The system needs to be individually designed for each property by a qualified architect and structural engineer, with methods followed by the letter.

Stage 1 Insertion of steel beams or Timber I beams.

Stage 2 Construction of load bearing timber wall from new beams to first Knuckle joint.

Stage 3. Insertion of new high grade timber rafters bolted alongside each truss top, creating new perimeter section.

Stage 4. Careful removal of each intermediate truss section. We have basically re built a new traditional design roof structure beneath the existing timber truss structure without removing the tiles above.

Don’t forget if any of the above is difficult for you to determine, we at TLS will do this for Free!