Green Roof Construction

sedum roof construction blog for roundhouse

We strive to be different, to challenge the norm and to ensure that our strong values consistently permeate the choices we make in all aspects of life. To this end, the project we are undertaking is a reflection of us and unique in many ways and with this comes a great many challenges not to be found in an off the shelf, replicable product.

Detailed here is the first big challenge of the build. This was to be found in the many stages of the build-up that forms the substantial roundhouse roof. Thankfully this challenge was undertaken by the inimitable Dylan Walker and his team at Artizans of Wood. This stage took several weeks and a lot of long hours to complete, luckily we were blessed with a lot of glorious September sunshine and very little rain. One storm part way through sent the team back to West Sussex to rest and to sleep in proper beds. Their commitment to this project was so inspiring, we can’t thank them enough for all the work they put in to creating a truly beautiful roundwood frame and roof.

Ceiling Timbers

Beautiful larch ceiling boards coated in eco-friendly fire retardant

Artizans of Wood sourced beautiful Norfolk feather-edged larch boards for the ceiling timbers. Just look at all those amazing grain patterns!

They needed to be fire-treated to meet Building Regulations requirements and we managed to find an eco-friendly product for this which needed to be brushed on - this took hours and hours as there were about 150 timbers. I was grateful for lots of summer sunshine and for all the help I received from Elliot and little Dylan.

Once they were fire-proofed we handed them over to the Artizans of Wood team to fix them on top of the reciprocal roof rafters. They managed to cut them to size to fit the segments of the roof and lay them perfectly on the uneven roundwood rafters - not an easy challenge! Doesn’t the ceiling look absolutely stunning? It draws your eye upwards and highlights those awesome larch reciprocal rafters and the magnificent skylight, to look upon the vastness and beauty of the Norfolk skies.

Roof Timbers and Sheep’s Wool

The next stage of the roof build up was to add the insulation, secondary rafters and cross ventilation.

The insulation helpfully arrived during a rainstorm and with all the family helping out we managed to get it quickly undercover, filling the garage and conservatory with the not unpleasant smell of slightly soggy sheep. With sustainability at the core of all of our decisions regarding the roundhouse build we chose to insulate with Black Mountain sheep’s wool, a beautifully tactile, natural and risk-free material to work with as opposed to the commonly installed fibreglass insulation that comes with a list of health risks reminiscent of asbestos.

The Artizans team fixed secondary rafters on top of the ceiling timbers which created the required overhang of 450mm to protect the straw bale walls. They laid the insulation between these rafters.

On top of these secondary rafters, battens were fixed horizontally and then vertically - these create a ventilation space above the insulation to allow moisture to be carried out of the top of the roof and away from the sheep’s wool and wood.

SmartPLY OSB boards were fitted on the cross battens to give a base for yet another layer of roof.

Beautiful Sedum

The next stage was fitting the butyl liner to waterproof the roof and laying the beautiful sedum.

These were the last stages of Artizans’ work on the build and to show their commitment having never fitted a green roof to a roundhouse before Dylan and Paddy undertook training to ensure they were fitting the waterproof lining correctly.

We’re so pleased with Dylan’s idea for how to finish off the edge of the roof layers. They fixed naturally wavy larch boards that curved around the roof creating the most beautiful finish to the roof overhang. In addition they fixed more larch ceiling timbers to the underside of the overhang.

A felt matting was laid on top of the waterproof liner to retain moisture for the sedum plants and to give some hold so that the sedum didn’t slip down the 26 degree roof pitch.

The beautiful sedum is Lindum SedumPlus Mat which has sixteen varieties of sedum to offer a variety of colour, as well as enhancing biodiversity. It arrived on pallets and after a week or so it was decided that it should be laid out on the ground underneath a nearby Oak Tree to enable the plants to breathe and receive sunlight. It did seem odd laying sedum mats on top of grass but it meant that when the time came to actually laying the sedum on the roof there were lots of happy plants. Nick, one of the Artizans team was given the task of climbing up the ladder multiple times with arms full of sedum and laying it neatly on the roof - not a job if you’re scared of heights.

A truck with a sedum roof

Colours we hope to enjoy range throughout the year from greens to vibrant reds, oranges, purples and browns. As well as offering a huge variety of colour, the different plants offer many different leaf types and flowers, resulting in a blend of beautiful textures. It already looks lovely settling in on the beautiful roof, allowing the roundhouse to blend perfectly with its natural surroundings.

Elliot and Dylan were certainly inspired by all the green roof action and decided that the truck roof needed a bit of greenery!