Research into the problems caused by driving rain on exposed solid

stone buildings

DAMP TOWERS PROJECT

English HeritageUniversity of OxfordSheffield Hallam UniversityColin BurnsRidout AssociatesArchitects and Contractors

This talk

• water penetration

• potential remedies

• climatic futures

• the research project: site testing and monitoring

laboratory simulations

results

The Problem

• failed repairs

• construction history

• moisture movement

• testing & monitoring

St Michael’s, Princetown

Ypres Tower, Rye, E Sussex

St Senara, Zennor, Cornwall

Winter rainfall predictions

Winter daily windspeed predictions 2050s

Source: UKCIP, 2002

Traditional Repairs

• stonework

• pointing

• rendering

• grouting

• plastering

Questions to answer

• how does driving rain enter solid masonry?

• how does water, moisture, vapour move within solid masonry?

• what difference does wind pressure, humidity, time, temperature make?

• are there differences in types of rain?

Questions to answer

• what are relative differences between remedial treatments?

• are there examples of similar towers performing differently

• which treatments work best?

• to what extent are human faults responsible for performance?

Holy Trinity, Challacombe, Devon

Castle Drogo

St John the Baptist, Stowford, Devon

Laboratory Testing

Sheffield Hallam University

Sheffield Hallam University

Wall 1

Smooth Render

Wall 2

Weatheredjoints

Wall 3

Coarse finished render

Wall 4

Repointed with OPC

Wall 5

Control

Results of Phase 1

• walls built with cement wetted up quickest & dried out slowest

• walls built with hydraulic and non-hydraulic lime mixes gave similar results

• walls built with hydraulic lime renders took longest to wet up and dried out quickest

Run 1Run 2Run 3Run 4Run 5Run 6

Start date03/08/200416/09/200409/05/200504/10/200524/01/200602/05/2006

TestingWalls 1 & 2 as builtWalls 1 & 2 as builtRendered walls 1 & 2, walls 3 & 4 as builtWalls 1,2 ,3 & 4 all renderedWalls 1 & 2 plastered, walls 3 & 4 renderedWalls 1 & 2 plastered, walls 3 & 4 grouted & un-rendered

Tentative Results from Phase 2

• whole of the wall acts as a system

• saturated walls without voids do not discharge water on the inside face

• walls with voids do discharge water on the inside face

• size of voids does not seem to make any difference

Tentative conclusions

• render is very effective at reducing water intake in voided walls

• lime putty render takes on more water but dries faster than hydraulic lime render

• grouting very effective especially for large voided wall during prolonged rain

• grouting only effective when voids filled

• plaster effectively reduces rain penetration

University of Oxford

Wytham, nr Oxford

Application to lighthouses

• understand the problem

• treatments depends on building & problem

• building needs to be considered as a complete system

• use traditional materials

• controlling indoor environments

• maintenance and monitoring