Capel Celyn

Capel Celyn was a rural community in the Afon Tryweryn valley, northwest of Bala. In 1965, the village and surrounding valley were flooded to create Llyn Celyn, a reservoir supplying water to Liverpool and the Wirral for industrial use.

Capel Celyn was one of the last Welsh-only speaking communities, and when the valley was submerged, its buildings—including the post office, school, and a chapel with a cemetery—were lost.

Understandably, the local Welsh-speaking communities strongly opposed the project. They fought hard to prevent the reservoir’s construction, even marching in London in protest.

The Capel Celyn Memorial Chapel was designed by Welsh sculptor R. L. Gapper of Aberystwyth. His intention was for the building to resemble a boat, symbolising how the culture and religion of the community survived the flood. The choice of local, re-used stone was meant to root the building in its historical place. The chapel was built on the site of the lost farm Gwern Delwau, and many stones from this farm, the original chapel, and other buildings from old Capel Celyn were incorporated into its construction. The memorial garden, which houses gravestones relocated from the original village, is surrounded by boulder field walls that also include the date stone from the original chapel.

One of the chapel’s most distinctive features is the angled window, positioned to overlook the site of the original chapel.

The flooding of Capel Celyn sparked widespread opposition within the Welsh community, and the phrase "Cofiwch Dryweryn" ("Remember Tryweryn") became a symbol of resistance. The motto urges Welsh speakers to remember the destruction of their communities and to protect their language.

Restoration Project

Due to the chapel's exposed position, and having undergone minimal maintenance for 50 years, Welsh Water took the opportunity to carry out extensive repair work. The building’s location means it is subjected to severe wind-driven rain almost all year round, which significantly affected the internal walls. The use of sand and cement mortar during its original construction prevented the walls from breathing, leading to persistent moisture retention and the growth of green algae.

The original long viewing window and entrance door had suffered from poor past repairs and had deteriorated beyond salvage. Additionally, vandalism and lead theft caused roof damage that required urgent attention.

Our company won the tender for the restoration work in April 2019, based on a competitive technical response-based bid.

Scope of Works

All external and internal walls were deeply raked out. The outer walls were repointed using a denser hydrated cement and coarse sand mix, which was chosen for its improved breathability while being less vulnerable to failure than a purely lime-based mortar. (It should be noted that this may not have been the contractor’s preferred choice.)

The internal walls were repointed using hydraulic NHL2 lime mortar, allowing moisture to wick through the walls and breathe back out, improving moisture management. While some minor moisture ingress was still present in severe weather, the repointing significantly reduced overall dampness in the building.

The roof was repaired, and tern-coated stainless-steel flashings were installed at all slate and parapet wall junctions, replacing lead to prevent future theft.

The original timber slit louvres had deteriorated beyond repair. After an extensive but unsuccessful search for a company to design and manufacture bespoke replacements, it was decided to use our own local fabricator, and the work was completed in-house. The new stainless steel-framed glass louvre windows were installed, allowing more light into the south end of the building. The thinner glazing also improved cross-ventilation, further enhancing moisture management.

After studying historical photographs from when the building was first constructed, a new 4.5m-tall viewing window was manufactured from Accoya—a highly durable timber particularly suited to Llyn Celyn’s harsh weather conditions. A new entrance door, built from the same material, was also installed to match the original design.

To complete the project, the large slate memorial plaques were cleaned, oiled, and reframed with clear protective screens to ensure their long-term preservation.

Completion and Public Reception

Upon completion of the works, Welsh Water held an open day, allowing visitors to see the restored chapel. The event received a great deal of positive feedback, including from relatives of the original Capel Celyn village, who expressed their appreciation for the careful restoration of this important historical site.