Candie Renovation
Renovation of Candie Gardens Greenhouse – 2006
by Stuart Horsepool
The complete renovation of the Lower Greenhouse at Candie Gardens would have to go down as one of our more challenging and interesting projects undertaken. As a working greenhouse, the Lower Greenhouse in Candie Gardens is now ready for use again.
.jpg "The Candie Greenhouse Before Work Commenced")
The greenhouse dates back to 1792 and it is believed to be one of the earliest examples of a greenhouse in the British Isles and as such is an important historical building to Guernsey. Despite needing extensive renovation work the greenhouse was still in use by States Works to cultivate the floral displays in Candie during the summer.
This project was undertaken for the Environment Department and was managed on their behalf by Martin Gavet and with advisory services from Malcolm Heath from the Heritage Department.
The greenhouse had fallen into a dangerous condition of almost total disrepair so the renovation covered the whole spectrum of repair work. To start with the greenhouse had to be stripped back of all the old paint on the outside which in turn revealed the true extent of the rot which from a distance was not easily seen. Two of the main beams (rafters) had deteriorated so badly they could not be saved so had to be replaced, and four other main beams had scarf repairs carried out saving as much existing timber as possible.
.jpg "Work In Progress")
Wood from Douglas Firs (Pseudotsuga Taxifolia) which has a straight grain with very few knots has been used on all the main repairs, it also retains its natural oils well which helps with preserving the timber. Joinery grade timber (Pinus Sylvestris) was used for the smaller joinery repairs. All the roof opening lights and the front opening sashes have either been repaired where possible or new ones made and have been fitted so they now open which will allow essential ventilation back into the building.
The roof of this greenhouse has a unique design as the glazing consists of what is known as fixed and sliding sashes, where the sash fits into rebates of the main beams unlike more modern glazing as we see now. It was these sashes that created the majority of work as when the rafter capping was removed most of the sashes were in need of repair or replacement. Sixteen out of twenty sashes were taken out and renovated and all but one of the top rafter caps was found to be in poor condition and have been replaced.
All the timber old and new has been treated with a special coat of linseed oil which feeds the wood. Then it had three coats of Alback/Holkham Linseed paint which was chosen by Heritage as it is non-toxic and also provides a longer durable finish and contributes to the preservation of the timbers.
The main constituents of Holkham Linseed Paints, apart from linseed oil, are Zinc Oxide and Titanium Dioxide. These constituents are infinitely safer to use than the lead paints used for many years on greenhouses and should ensure its protection. The linseed oil in the paint gradually oxidises with the air over the years and fades..jpg "Restored To It's Former Glory")
When this happens it is recommended to give a further coat of warm raw linseed oil. The next treatment would be after 6-7 years which would be a single coat of linseed paint. This is still one of the oldest paint systems used but it requires warmer temperatures to dry and up to 48 hours between coats so is not favoured by today’s painters. When we painted the Candie greenhouse we had to wait for temperatures to rise suitably and consistently, which this year was not until later in June.
This was a unique project to be involved in and we have worked as closely to the Victorian way of building as we possibly could.
We have used mortise and tenon joints fixed with traditional timber dowels therefore eliminating the use of nails which after a period contribute to rotting timbers with rust etc. This project gave my team the opportunity to use a variety of their carpentry skills and to learn from the Victorian methods of construction. As with all old buildings and structures they need regular, continual maintenance to ensure a long lifespan. I believe as a result of our work on the Lower Greenhouse at Candie Gardens we have helped secure its future for many years to come so it can continue to provide a service and enjoyment to the public.