Nigel Gervis, Founder & Technical Director,
Ty-Mawr Lime Ltd
The Benefits of Lime
Building Regulations - Context
Guide to the Conservation of Historic Buildings
• The standard includes information such as walls can be 30% less energy efficient if damp and good repair provides greater energy efficiency. (Section 5.3.1)
• Impervious materials can be harmful including cement pointing and rendering and most types of impervious solid wall insulation and the Standard states that removal should be considered.
• Section 5.3.1 states ‘some energy efficient measures can have an adverse effect on sustainability’.
• Section 7.4 on materials emphasises that ‘the removal of historic fabric and patina should be avoided as far as possible to retain authenticity’.
• Section 0.1 highlights that British Standards that are applicable to newer buildings might be inappropriate.
British Standard 7913 British Standard 7913
Solid Wall Construction – Simple & Robust
Building Health
1.64
0.60
0.460.37 0.32 0.28
0.20
2.20
0.660.50
0.400.34
0.29
0.00
0.50
1.00
1.50
2.00
2.50
40mm 60mm 80mm 100mm 120mm 180mm
W/(
m2
K)
Insulation Thickness Wood Fibre or Expanded Cork
Limestone 600mm Slate 600mm
What effect do different thicknesses of insulation really have?
Wall Types
The Lime Cycle
Clay,
sand,
straw,
earth
Pure/
Lime Putty
Feebly
hydraulic
NHL2
Moderately
Hydraulic
NHL3.5
Eminently
Hydraulic
NHL5
Roman /
Natural
Cement
Ordinary
Portland
Cement
Other Names Cob /
clom
Fat, High
calcium,
White Chalk,
Air Lime
Slightly
hydraulic, grey
chalk, semi-
hydraulic
Pure natural
XHN 30
(France), semi
hydraulic
Pure
natural
XHN 60
(France)
Parkers
cement,
eminently
hydraulic lime
(Italy)
OPC
Set In Water None None 15 to 20 days
or more
6 to 8 days 2-4 days Initial set in
the order of
15 minutes to
2 hours
Initial set
30 minutes
Final set 6 -
10 hours
Impurities Negligible Under 12%
active clay
12-18% active
clay
18-25%
active clay
Up to 55%
active clay
N/mm2 Up to
0.77
0.3 to 0.5 1.3 to 2.0 2.0 to 5.0 5.0 to 10 10 and above 28 to 50+
Types of materials Types of Materials
Building Health
Building Health
For further information…….
www.lime.org.uk
For further information…….
…and catalogue, information leaflets, newsletters
…and catalogue, information leaflets, newsletters
For further information…….
Practicing what we preach…..
…you are very welcome visit or come on a course!.
Repair within the rules….simple and appropriate