This good practice is linked to the following European Green Leaf Award indicators:
- 1. Nature, biodiversity, and sustainable land use.
- 3. Waste and circular economy.
Purpose
The Municipality of Elsinore wants to reduce the climate and resource load in connection with construction, which was the driving force to recycle the tiles when the roof at Sindshvile had to be replaced, which has a large CO2 saving as a result.
Initiative description
It was clear that the lower roof of a large municipal administration building, built in the early 1900s, had to be replaced. After many years of history, and continuous replacement of individual tiles, it was finally worn out. However, the rafters and the more than 1,000 m2 of tiles were not, and they were therefore carefully dismantled, cleaned of mortar, and reused in the renovation process.
When Kyed Byg A/S took on the task, it was not finally decided that the tiles would be recycled, but since economic calculations showed that the additional cost would be sufficiently small compared to the CO2 savings, it was finally decided to preserve the old tiles.
Given that this process is more time-consuming than installing a roof with entirely new tiles and the gentle removal of the old tiles, the schedule was devised accordingly. Despite its complexity, the schedule was followed, ensuring that the task was completed within the stipulated timeframe.
As part of the renovation, the entire roof structure has been reviewed, and most of the underroof needed replacement. All wood used in the renovation process bears the PEFC certification, guaranteeing its origin from sustainably managed forests. The rafters, which could still be used, have been repaired for minor damages and treated with insecticide to extend their shelf life. All new parts have been fire-impregnated, and in general, all new materials have been chosen based on being able to match the durability time of the recycled tiles, so that the result is a roof where all parts have approximately equal longevity.
A few tiles were lost in the dismantling process, and therefore the project was supplemented with tiles from a previous project at the Grydemose School. Being able to pick up additional tiles locally, made the project save both transportation time, fuel, and extra costs.
Challenges
The market for circular construction is currently very limited, and the local carpentry company, that has been responsible for the renovation, had not previously worked with recycled tiles to this extent, and therefore there was a lot of learning along the way.
New tiles are completely uniform and come with a guarantee and data sheet for installation, but the old tiles are uneven and made the laying difficult, which meant that the craftsmen had to invent the good solutions along the way and also had to make some test laying so that they could find the best technique.
It also required learning to dismantle the tiles gently, as well as to have them transported down from the roof, cleaned them, packed them, and put them in repository without them breaking.
One of the challenges of using recycled materials in construction is that it can be difficult to provide a guarantee on the product. All the new products used in the renovation of the roof come with a warranty, which expires after 30 years. A similar guarantee could not be extended to the recycled tiles. Consequently, Kyed Byg reached an agreement with the developer that Kyed Byg will undertake repairs for up to 10 tiles, at no additional expense, within one year following the completion of the assignment.
Stakeholders
Kyed Byg A/S (main contract), The Municipality of Elsinore (developer), North Zealand Parks and Roads (NSPV).
Results and benefits
With a final price of approximately DKK 4 million, the additional cost of recycled tiles ended up being 4 percent, which is negligible compared to the CO2 savings. The project has generated a total saving of 238 tons of CO2, which corresponds to 4.5 kg CO2/m2/year, which new tiles would have cost on the CO2 accounts.
Lessons and recommendations
Figuring out how to handle the old tiles and finding workflows that worked was crucial to being able to preserve the tiles at all. For example, getting them gently off the roof was crucial to be able to reuse them afterwards.
From repository on pallets, the tiles had to be reinstalled on to the roof, and here it was a point of attention that the tiles were evenly distributed on both the south side and north sides of the roof. Over the years, the tiles on each of the two sides have patinated differently, and for the result to be an even play of colours, attention has been paid to the restoration of each single tile.
When techniques are foreign to the craftsmen, practice is a prerequisite. Therefore, Kyed Byg made some test laying prior to the final laying of the 1,000 m2 roof, which provided great value.