GBE L15 External Solar Shading (Outline)

GBE > Encyclopaedia > Code > Outline > G#41109

Legend:

Outlines are the essence of the topic in a hierarchical order
They could become the core of an Expert System or Design and Decision Tool
The colour coding in the word file highlights:
- Green Environmental Options
- Violet Normal Practice
- Red Missing information
  - (in the book it was extracted from)

Green: Consider for GBE

E.g. of approach:
FSC only
Preservative treatment: Avoid if possible

Blue: for TRADA but not GBE

FSC and PEFC
Treated softwood
Painted softwood

Violet: Avoid not for GBE

Treated softwood
Nails make demountability less successful

Red: Pending information by me or clarification from Patrick Hislop

Outline:

GBE L15 External Solar Shading Outline

Outline of timber constructions in readiness for an expert system and specifications
Extracting the essence from TRADA Weatherboarding publications by Patrick Hislop

L15 External Solar Shading Outline

Performance requirements

Maximise view/restrict viewing angles
Minimise sunlight penetration (avoiding glare and overheating internally)
Maximise daylight penetration (reduce use of artificial lighting)
Maximise reflection of daylight off surfaces
Minimise reflection of sunlight from surfaces
Maximise Ultra violet light absorption upon reflection from surfaces
Resist wind load and uplift
Not generate wind noise or rattling
Resist defection and creep
Durability
Security screen
May for maintenance access walkways
Support loadings

Arrangements

Flush with wall cladding
Vertical integral and flush with cladding in front of window
Vertical in front of window
Vertical projecting at side of window
Vertical spaced from the window
Vertical surrounding balconies
Projecting/Horizontal
Horizontal projecting from window head
Horizontal projecting from window forming light shelf
Horizontal above flat rooflight
Horizontal above balconies and roof terraces
Projecting/Sloping
Sloping above sloping rooflight and conservatory roof
Sloping projecting from window head
Combination(s) of the above

Design

Integral/flush with /same detailing as wall cladding
Rainscreen approach open jointed cladding system
Alternate boards/battens continue across window
Alternate boards/battens/blades continue along walls
Independent
Panelised
Unframed
Framed
Hardwood framed
Same durability as blades
Sub-framed
Metal frame
Mild Steel
Hot dip galvanized
Sacrificial coating of zinc rich epoxy paint if acidic timber

Blade orientation

Vertical
In vertical or sloping installation
Greatest resistance to deflection and creep
Greatest spanning potential
Top surface profiled for rainwater runoff
Drip profile at base
Sloping (normal to the sun’s rays)
In vertical installation
Offers some resistance to deflection and creep
Design to overcome deflection and creep
Seek to obtain stiffness from supports and fastenings
Encourages rainwater runoff, the steeper the better
Drip profile at base
Horizontal
Poorest spanning potential
Design to overcome deflection and creep
Seek to obtain stiffness from supports and fastenings
Risk of rainwater standing on top
Risk of staining
Risk of runoff and condensation on bottom
Risk of staining
Consider self weight and wind loading

Shading array dimensions

To exclude sun at 56 degrees above horizontal (UK summer)
To permit sun at 10 degrees above horizontal (UK winter)
To exclude/permit sunlight at other angles (to suit brief)

Blade Size and Spacing

Narrow blades/battens/boards
Closer spacing to exclude sun

Wide blades/battens/boards

Wider spacing to exclude the sun
Spacing to encourage consistent bleaching of unfinished timber

Species

Generally
Strong stiff species for spanning
Douglas Fir
Preservative treated
European Larch
Low self weight if horizontal (shallow slope)
Western Red Cedar
Strength stiffness and low moisture movement
For long spans between supports
Durable Tropical hardwoods
Durability class 1 or 2
Sapwood removed
Unfinished
Durability class 3 4 or 5
Preservative treated
Softwood
Local
Native
European Larch (Larix deciduas)
care with Sustainable Certification
Class 3 moderately durable
Small movement
Less dense, strong and knot-free
Also suitable for shingles and shakes
Non-native
Western Red Cedar (Thuja plicata)
UK grown less durable than North American class 2
Remove sapwood
Small knots common in UK grown
Small movement
Lightweight
BS 8417: 60 year service life
Resistant to preservative treatment
High tannin content corrosive: protect porous and steel or iron materials below
Soft and brittle:
Avoid applications prone to mechanical damage: low level
Solar shading with single fixings subject to rotation torsion
Avoid unfinished where high levels of pollution present (traffic and industrial processes)
Also suitable for shingles and shakes
Douglas Fir (Pseudotsuga menziesii)
(UK grown less durable Class 3-4 moderately to slightly durable than North American Class 3)
Resistant to treatment
Can be left unfinished to fade
Requires preservative treatment
European Larch (Larix deciduas)
care with Sustainable Certification
Class 3 moderately durable
Small movement
Also suitable for shingles and shakes

Hardwood

Fixings/Framing

Acidic timber
Acidic timbers need stainless steel fasteners
Wood to wood
Wood to galvanized
Frame often galvanized mild steel
Predrill mild steel and hot dip galvanized
Austenitic stainless steel and galvanized steel are incompatible
but large amounts of galvanized steel can cope with small amounts of stainless steel
Do not use self drilling self tapping stainless fasteners into galvanized
Isolate metals with grommets, sleeves and washers
Remove all metal swarf to avoid tannin corrosion and staining
Non acidic timbers
Non-acidic timbers externally need corrosion resistant fasteners
stainless steel fasteners (screws bolts washers)
Wood to wood
Frame often galvanized mild steel
Predrill mild steel and then hot dip galvanized
Galvanized steel fasteners (nuts bolts washers)
Wood to galvanized
Do not use self drilling self tapping fasteners into galvanized
Fastenings

Generally

Strength needed at supports
Minimum 2 fasteners to overcome wind loading twisting rotation stresses
Minimum 2 fasteners to overcome moisture movement shrinkage
Minimum 2 fasteners to overcome drying distortion in green timbers
Low density timber
Prone to early failure
Species:
Western Red Cedar
Heat treated timbers
High density timbers
Still use two fasteners
Overcome tendency to distortion in drying shrinkage
Panelisation
Offsite preassembly
Rigid panels for handling
Fix back to structure at larger centres
Notched members receive notched blades
Helps overcome distortion
Reduce span of blades
Fixing
Screwed and glued
Gluing may help prevent rattling

Revisions

Revision No.	Description	Author	Date	Checked by:
A00	Created issued to SP to start process rolling	BRM	02/05/2008
A01	Revised refinement and development using TRADA Cladding guide 2^nd edition (incomplete)	BRM	06/05/2008 – 17/05/2008
A02	Revised refinement and development using TRADA Cladding guide 2^nd edition (complete) Reorganised content list, H21 and Added K42	BRM	26/05/2008
A03	Continue to add to scope and to H21 (complete)	BRM	12/06/2008 – 19/06/2008
A04	K13 (internal) copied to H20 (external) new K13 similar to H20 pending editing Specification clauses now in a separate file Minor refinements Issue to Sandy	BRM	26/06/2008 – 03/07/2008 & 31/10/2008
A05	Rename GBE H21 Outline from TRADA Book.docx	BRM	26/02/2016
A05	Replace GreenSpec with GBE	BRM	26/02/2016
A05	A few tweaks for TDUK issue (H21 only)	BRM	10/07/2023
A05	Issue to MM at TDUK	BRM	10/07/2023
A06	Split the file L15 from H21	BRM	21/08/2023

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GBE L15 External Solar Shading (Outline)

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