2008 changes to the Scottish Technical Handbooks

by John Boanson
Architect/ Technical authoring coordinator

Although quoted as “minor changes and corrections”, there are some areas worth looking into further. These are not just spelling corrections and format changes, some do indeed change the technical content of the guidance.

The revised edition of the Technical Handbooks came into force on 1 June 2008. While the introduction to the changes say that “ . . . there are no technical revisions, corrections have been made in sections 1, 2, 3 and 6” . These corrections need to be looked at as they may have a technical effect on your buildings. I have worked through them and below bring to your attention the more significant ones:

Domestic Technical Handbook

SECTION 1 – STRUCTURE:

Annex 1A – General
1.A.1 The maximum length for timber framed walls between supporting walls has been reduced from 10 m to 9 m.

Annex 1C – Foundations
1.C.6 In classes 11 for medium dense gravel or sand and class V for loose sand, silty sand or clayey sand, the cross section of the peg used for classification of the ground has been changed from 50 mm² to 50 x 50 mm.

Annex 1E – Timber frame walls
1.E.3 The maximum height of the building in the first diagram has been reduced from 15 m to 10 m.

Annex 1F – Timber floors and roof members
1.F.3 The grade combinations to satisfy the strength classes for Canadian Sitka spruce have been changed.

The strength class C24 for Douglas Fir-Larch and Hem-Fir from USA have now been correctly aligned.

1.F.4 For floor and flat roof joists, the minimum distance from the edge of a hole to a support to be 0.25L, not 0.07L.

1.F.9 For timber strength class C24, the permissible clear span for a 38 x 195 mm joist with a dead load between 0.50 to 1.25 kN/m² has been reduced from 3.89 m to 3.39 m.

SECTION 2 – FIRE:

2.0.4 Sector specific guidance has been referenced for various building uses on compliance with Part 3 of The Fire (Scotland) Act 2005.

SECTION 3 – ENVIRONMENT:

Changes consisted of replacing incorrect words with the correct ones. These indeed were minor changes and I don’t think anyone’s projects will be affected.

SECTION 6 – ENERGY:

6.0.13 This new clause which gives guidance on the requirements of EU legislation has been added.

6.1.2 Note 5 has additional words explaining the original intention, i.e. if the area of the exposed façade is less than 25% of the floor area, then the area for the windows, doors and rooflights is to be taken as the total exposed façade area for the notional dwelling.

6.2.13 Added guidance explaining that whilst the U- value recommendations should be met, the percentage of glazing is unrestricted.

Non-domestic Technical Handbook

SECTION 1 – STRUCTURE:

No changes.

SECTION 2 – FIRE:

2.0.4 Sector specific guidance has been referenced for various building uses on compliance with Part 3 of The Fire (Scotland) Act 2005.

SECTION3 – ENVIRONMENT:

No significant changes.

SECTION 6 – ENERGY:

6.0.13 This new clause which gives guidance on the requirements of EU legislation has been added.

In summary, while there are not a lot of changes and they may not be considered major, but if they do impact on your building, then their effect could well be significant.

 
Related NBS information:

Articles:

• An overview of the changes to the Scottish Technical Handbooks 2007

Selected links:

• Official and governmental information, UK

Written October 2008

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