Week 6: Building the roof structure

Posted by on Apr 18, 2013 in Warm EnerPHit office | Comments Off on Week 6: Building the roof structure

Work is focusing this week on finishing the roof structure, which has brought plenty of challenges. We talked last week about how difficult it has been to ensure that the OSB could be laid flat enough on such a wonky structure. It has taken a huge amount of time and effort for the team to get this right but they’ve done a sterling job.

The weather continues to be temperamental. This creates its own issues for our build: the mineral wool insulation will be damaged if it gets wet and it’s time-consuming to have to keep covering and uncovering the roof. So, the build team need to ensure a long enough gap in the rain to be able to get the insulation on a whole section of the roof all in one go, which could, potentially, hold things up. Luckily we’ve got a good forecast for the next few days as the insulation is due to arrive on site today.

I beam, membrane, tape rs

I-beams in place over the airtight membrane

Lessons in ensuring you’re using the right materials…

Alex, our site foreman, highlighted a problem encountered on site this week: four varieties of Knauf sealing tape arrived on site, with all details written in German – not easy when no-one on site speaks German! The white LDS Soliplan tape was listed as suitable for joining the membrane on the roof, so last Friday the team set to, using it to seal up the airtight membrane on the first section of roof.

After a weekend of rain, Alex came back on Monday morning to discover that it had all peeled off! Close inspection revealed that the tape was in fact paper-based! The whole section then had to be resealed using the blue Solifit tape instead. It was really lucky that we were able to pick this up early on though, when only part of the roof surface had been sealed, and it was only a small setback.

…and experiences inside

When showers force the team back inside there’s still plenty to be done inside. Robbie has been working on the boxing for the pipework and I asked him how he found working on a low-energy build compared to a standard build: “It makes you really concentrate!” he said, “But you can feel like you haven’t achieved much in a day because the pace needs to be slower. You have to be super careful not to puncture the air tight membrane so there are certain areas that you can’t fix as you normally would, you have to glue everything that goes in instead.”

He also explained that the quality of the materials used becomes more important too. The team have to select pieces far more carefully than they would on a standard build, making sure they aren’t twisted etc. Normally fixing would sort out or overcome any issues like that, but when you’re relying on glue you have to make sure the materials are right at the outset.

Getting ready for the next airtightness test

We’re planning on our third airtightness test taking place tomorrow. Work today will focus on sealing the roof membrane to the outside wall and ensuring the whole structure is sealed. Fingers crossed the reading will have come down significantly from the 6.4 ach@50Pa test pressure – will we be able to meet the 1 ach needed for the EnerPHit standard?

Roof week 6 rs