Rising damp evaluation and treatment A quasi-experimental case study

Dr Les Sellers BSc(Hons), Dip HI, MRICS, FCABE, C.Build E, CEnv, CSSW, CSRT 2

L Sellers 2018 Content

1. Why? 2. How? 3. Findings. 4. Outcome. 3

L Sellers 2018 Project protocol

▪ Locate a house with damp walls. ▪ Confirm rising damp. ▪ Construct five treatment test panels. ▪ Install apparatus to monitor the moisture change in the test panels and the environment. ▪ Quantify the moisture content of the test panel walls at the start and end of the monitoring period. 4

L Sellers 2018 Gravimetric analysis method

▪ BRE Digest 245: Rising Damp in Walls. Diagnosis and Treatment.

BRE Digest 245 (Trotman, Laboratory balance and drying 2007) oven.

Desiccator containing a saturated salts solution. 5

L Sellers 2018 The case study house

▪ Early twentieth century, brick-built, mid-terraced house. ▪ Type prone to dampness. 6

L Sellers 2018 The case study house: damp affected walls

OUTBUILDING

OUTBUILDING

▪ Visible evidence of KITCHEN damp and profile of Ground floor plan Protimeter moisture

illustrating the UNDERSTAIRSCUPBOARD meter readings damp affected consistent with ground floor walls. rising damp.

LIVING ROOM

ENT LOBBY 7

L Sellers 2018 The case study house: damp affected walls

▪ All sources of moisture other than rising damp systematically discounted. ▪ Gravimetric analysis of the hygroscopic and capillary moisture distribution confirmed rising damp. 8

L Sellers 2018 Allocation of test panels

▪ Panel A: drill holes into OUTBUILDING the wall base and install damp proof course OUTBUILDING cream. ▪ Panel B: apply low- permeability cement render.

KITCHEN PANEL A PANEL Redundant Ground floor plan flue ▪ Panel C: drill holes into

PANEL B PANEL the wall base, install illustrating CUPBOARD UNDERSTAIRS

location of the five PANEL C PANEL D PANEL E damp proof course test panels. cream, and apply low- permeability cement render. LIVING ROOM ▪ Panel D: drill holes into the wall base.

ENT LOBBY ▪ Panel E: no treatment (control). 9

L Sellers 2018 Moisture measuring apparatus installation

Panel C: moisture monitoring apparatus. 10

L Sellers 2018 Test Panels A & B

Panel A: moisture monitoring apparatus. Panel B: moisture monitoring apparatus. 11

L Sellers 2018 Test Panels C, D & E

Panels C, D, and E: moisture monitoring apparatus. 12

L Sellers 2018 Data collection: Protimeter measure-mode & search-mode

Protimeter measure- Protimeter measure- mode using Heavy mode using Deep Wall Duty probe. probes.

Protimeter search- mode. 13

L Sellers 2018 Data collection: timber probes and Hygrosticks

Protimeter measure- Protimeter measure- mode reading Type 1 mode reading plain embedded timber timber probe. probe.

Protimeter connected to Hygrostick. 14

L Sellers 2018 Data collection: Lascar data loggers

Panel mounted Lascar data logger Living room wall mounted Lascar displaying RH. data logger displaying RH.

▪ Data collection: every ten days for a total period of fifteen months. ▪ Forty-four data sets: each comprising 227-268 individual values. ▪ Lascar data loggers: 11,257 relative humidity and temperature data pairs. ▪ Data processing: Excel workbook. 15

L Sellers 2018 Final sampling

Panels C, D, and E: plasterwork made good. Panel B: final sampling. 16

L Sellers 2018 Results Panel D: drilling

Stage 2 Stage 3 (average) Stage 5 (average) ▪ Panel D: drilling holes Panel D: masonry Panel D: masonry Panel D: masonry Row TMC HMC CMC TMC HMC CMC TMC HMC CMC has no controlling effect 7 0.5% 0.7% -0.2% 0.3% 0.3% 0.1% 0.1% 0.2% -0.2% over rising damp. 6 0.0% 0.1% -0.1% 0.2% 0.3% -0.2% 0.0% 0.1% -0.1% 5 1.6% 1.6% 0.1% 0.9% 1.4% -0.5% 4 3.5% 2.3% 1.2% 9.9% 6.4% 3.5% 6.0% 5.3% 0.7% 3 4.6% 2.6% 2.0% 4.8% 1.8% 3.0% 1.3% 1.3% -0.1% 2 11.8% 2.7% 4.6% 9.4% 1.3% 8.1% 7.6% 1.6% 6.0% 1 11.7% 0.9% 10.8% 10.9% 0.7% 10.2% 10.0% 0.5% 9.5% 17

L Sellers 2018 Results Panel A: DPC cream

Stage 2 Stage 3 (average) Stage 5 (average) ▪ Panel A: installing the Panel A: masonry Panel A: masonry Panel A: masonry Row TMC HMC CMC TMC HMC CMC TMC HMC CMC damp proofing cream 7 0.1% 0.1% 0.0% 0.2% 0.3% -0.1% 0.0% 0.1% -0.1% effectively controls 6 0.9% 1.0% -0.1% 0.5% 0.6% -0.1% 0.1% 0.3% -0.2% capillary moisture. 5 1.9% 1.7% 0.2% 0.6% 1.6% -1.1% 4 6.3% 5.6% 0.7% 7.2% 6.1% 1.1% 2.7% 4.6% -1.9% 3 7.5% 5.2% 2.3% 8.2% 3.8% 4.4% 2.7% 2.6% 0.1% 2 12.9% 1.5% 11.4% 12.8% 1.6% 11.2% 3.2% 0.9% 2.3% 1 14.8% 1.0% 13.8% 15.0% 1.0% 14.0% 13.8% 0.4% 13.4%

Stage 2 Stage 3 (average) Stage 5 (average) Panel A: plasterwork Panel A: plasterwork Panel A: plasterwork ▪ Panel A: without Row TMC HMC CMC TMC HMC CMC TMC HMC CMC addressing hygroscopic 7 4.8% 5.1% -0.3% 0.7% 1.0% -0.3% 0.3% 0.8% -0.6% salt contamination of 6 2.8% 2.7% 0.1% 1.7% 2.2% -0.5% 0.9% 1.4% -0.5% 5 2.1% 2.4% -0.3% 1.8% 2.3% -0.5% the plasterwork, 4 6.3% 5.6% 0.7% 6.2% 6.6% -0.4% 2.1% 3.0% -1.0% dampness persists. 3 2.9% 3.2% -0.3% 2 1 18

L Sellers 2018 Results Panel B: low-permeability cement render

Stage 2 Stage 3 (average) Stage 5 (average) ▪ Panel B: low- Panel B: masonry Panel B: masonry Panel B: masonry Row TMC HMC CMC TMC HMC CMC TMC HMC CMC permeability cement 7 0.1% 0.3% -0.2% 4.5% 0.5% 4.0% 0.0% 0.1% -0.1% render provides a 6 0.3% 0.3% 0.0% 2.1% 0.4% 1.7% 0.1% 0.2% -0.1% significant controlling 5 3.8% 1.1% 2.7% 0.2% 0.6% -0.4% 4 4.6% 4.8% -0.2% 8.8% 2.5% 6.3% 3.1% 4.1% -1.0% effect, despite rising 3 0.8% 1.2% -0.4% 5.3% 2.7% 2.7% 3.4% 2.6% 0.8% damp persisting in the 2 9.8% 3.3% 6.5% 10.6% 1.5% 9.1% 9.4% 1.5% 7.9% substrate; 1 10.8% 0.1% 10.7% 10.9% 1.2% 9.7% 10.8% 0.3% 10.6% ▪ Panel B: low-

Stage 2 Stage 3 (average) Stage 5 (average) permeability cement Panel B: plasterwork Panel B: plasterwork Panel B: plasterwork render did not cause Row TMC HMC CMC TMC HMC CMC TMC HMC CMC capillary moisture to 7 2.9% 3.3% -0.4% 2.2% 2.2% 0.0% 0.3% 0.6% -0.3% 6 3.7% 3.9% -0.2% 2.7% 2.4% 0.3% 0.4% 0.6% -0.2% rise higher up the wall. 5 4.5% 3.0% 1.5% 0.4% 0.7% -0.3% 4 4.8% 4.8% 0.0% 6.3% 3.8% 2.5% 1.0% 1.1% -0.1% 3 6.6% 3.5% 3.1% 0.6% 0.7% -0.1% 2 7.1% 3.8% 3.3% 1.7% 1.3% 0.4% 1 8.2% 4.1% 4.2% 1.6% 1.3% 0.3% 19

L Sellers 2018 Results Panel C: DPC cream & low-permeability render

Stage 2 Stage 3 (average) Stage 5 (average) ▪ Panel C: installing the Panel C: masonry Panel C: masonry Panel C: masonry Row TMC HMC CMC TMC HMC CMC TMC HMC CMC damp proofing cream 7 0.4% 0.6% -0.2% 1.7% 0.4% 1.4% 0.0% 0.1% -0.1% and applying low- 6 0.0% 0.1% -0.1% 0.1% 0.1% 0.0% 0.1% 0.0% 0.1% permeability cement 5 2.2% 0.9% 1.3% 0.4% 1.0% -0.7% 4 4.8% 4.5% 0.3% 7.8% 3.7% 4.1% 1.5% 2.5% -1.0% render effectively 3 10.6% 6.0% 4.6% 11.1% 4.2% 6.9% 1.9% 3.2% -1.3% alleviates rising damp 2 11.8% 2.7% 9.1% 11.9% 1.3% 10.6% 0.5% 1.1% -0.6% by addressing both 1 11.3% 0.5% 10.8% 10.4% 0.8% 9.7% 0.6% 0.5% 0.1% capillary and hygroscopic moisture. Stage 2 Stage 3 (average) Stage 5 (average) Panel C: plasterwork Panel C: plasterwork Panel C: plasterwork Row TMC HMC CMC TMC HMC CMC TMC HMC CMC 7 0.8% 1.3% -0.5% 2.2% 2.7% -0.5% 0.3% 0.6% -0.3% 6 0.6% 0.7% -0.1% 2.4% 2.7% -0.3% 0.3% 0.6% -0.3% 5 3.6% 3.1% 0.5% 0.6% 0.8% -0.2% 4 2.0% 2.3% -0.3% 4.1% 3.9% 0.2% 0.6% 0.8% -0.3% 3 3.8% 3.6% 0.2% 3.9% 3.7% 0.2% 0.8% 1.0% -0.3% 2 3.8% 2.9% 0.9% 5.4% 4.1% 1.4% 0.7% 1.0% -0.3% 1 2.8% 1.6% 1.2% 5.6% 3.9% 1.7% 20

L Sellers 2018 Results moisture measuring apparatus: Protimeter

▪ Protimeter measure-mode and search-mode functions compromised by hygroscopic salt contamination. ▪ Hygroscopic salts affected the embedded timber probes: Protimeter measure- mode readings increased overtime. ▪ Protimeters will indicate if a material is dry and free of hygroscopic contamination. ▪ At best, the Protimeter provides a qualitative value of total moisture content. ▪ Not possible to know whether the value obtained is a result of hygroscopic or capillary moisture. ▪ The Protimeter is a useful instrument: gravimetric analysis supported the rising damp diagnosis suggested by the visible evidence and the profile of Protimeter readings obtained during the early stages of this study. 21

L Sellers 2018 Results moisture measuring apparatus: Hygrosticks

▪ External environment drives the vapour pressure and equilibrium relative humidity independently of the moisture content of the walls.

Panel C: Protimeter Hygrostick vapour pressure (4-period moving average) 3.00

2.50

2.00

1.50 Vapur pressure(kPa)

1.00

0.50

0.00

Date

4 per. Mov. Avg. (C7 Hygrostick vapour pressure) 4 per. Mov. Avg. (C6 Hygrostick vapour pressure) 4 per. Mov. Avg. (C5 Hygrostick vapour pressure) 4 per. Mov. Avg. (C4 Hygrostick vapour pressure) 4 per. Mov. Avg. (C3 Hygrostick vapour pressure) 4 per. Mov. Avg. (C2 Hygrostick vapour pressure) 4 per. Mov. Avg. (C1 Hygrostick vapour pressure) 4 per. Mov. Avg. (External Lascar vapour pressure) 4 per. Mov. Avg. (Living room Lascar vapour pressure) 4 per. Mov. Avg. (C2-C3 Lascar vapour pressure) 22

L Sellers 2018 Results moisture measuring apparatus: Hygrosticks

▪ Clear temperature gradient of 1-2oC over the height of the panels.

Panel E: Protimeter Hygrostick temperature (4-period moving average) 26

24

22

20

18 Temperature (oC)

16

14

12

Date

4 per. Mov. Avg. (E7 Hygrostick temperature) 4 per. Mov. Avg. (E6 Hygrostick temperature) 4 per. Mov. Avg. (E5 Hygrostick temperature) 4 per. Mov. Avg. (E4 Hygrostick temperature) 4 per. Mov. Avg. (E3 Hygrostick temperature) 4 per. Mov. Avg. (E2 Hygrostick temperature) 4 per. Mov. Avg. (E1 Hygrostick temperature) 4 per. Mov. Avg. (Living room Lascar air temperature) 4 per. Mov. Avg. (E2-E3 Lascar temperature) 23

L Sellers 2018 Results environmental moisture correlation

▪ Evaporation of moisture associated with rising damp could not be measured at the boundary layer of the panels and had no effect on the wider environment.

Lascar data loggers: vapour pressure (4-period moving average) 2.30

2.10

1.90

1.70

1.50

1.30 Vapur pressure(kPa)

1.10

0.90

0.70

0.50

Date

4 per. Mov. Avg. (External Lascar vapour pressure) 4 per. Mov. Avg. (Living room Lascar vapour pressure) 4 per. Mov. Avg. (Panel A Lascar vapour pressure) 4 per. Mov. Avg. (Panel B Lascar vapour pressure) 4 per. Mov. Avg. (Panel C Lascar vapour pressure) 4 per. Mov. Avg. (Panel D Lascar vapour pressure) 4 per. Mov. Avg. (Panel E Lascar vapour pressure) 24

L Sellers 2018 Implications for practice

▪ Rising damp is a real phenomenon that affects houses (i.e. remedial damp proof course treatments are necessary). ▪ Contemporary method of remedial damp proof course treatment—the cream and low-permeability cement render method—effectively controls rising damp. ▪ The commonality of rising damp was not determined but dampness affecting the case study house was not unique. ▪ Despite the limitations of an electronic moisture meter, rising damp can be diagnosed using non-invasive methods. ▪ Methods of measuring moisture that use relative humidity or vapour pressure are compromised by the effect of moisture in the wider environment and measurement equipment requires a robust testing protocol. ▪ Results provide clarity and assurance to building professionals and homeowners, with regard to the phenomenon and treatment of rising damp. 25

L Sellers 2018 Finally

▪ Thesis ‘Rising damp evaluation and treatment: a quasi-experimental case study’ is available from University of Salford's Institutional Repository: ▪ http://usir.salford.ac.uk/43721/ ▪ Thank you for listening. 26

L Sellers 2018

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