Timber Strength - how to increase it invisibly
 
 We are a National Service - with local Specialist Surveyors
 


Types of weakness that can be repaired

1. Bending/deflection - caused by overloading, undersized timber section, poor quality timber, insect or rot damage

2. Change of Use - from domestic to commercial, added loading such as: storage, filing, piano, Museum

3. New Build - need for lowest height of timber to preserve headroom, loft conversion, ring beams, ridge boards, joists

4. Breakage - partial or complete failure

Total failure due to severe insect attack

Overloaded Rafter
Example

Barn, Somerset - overloaded tie beams in a barn now carrying heavy clay tiles on the roof (had been a thatch and then galvanised sheeting).

Loft Conversion, Newton Abbot - maximum ridge board to be 12" x 4" (300mm x 100mm), not strong enough to meet Engineers specification.

Beam upgrade with re-connection of joists

Upgraded Floor Beam


How to increase strength

Upgrade the Beam or Joist - cut a slot, or slots, along the length to within about 40mm of the base and bond in BS4449 High Tensile Rebar with Structural Epoxy Pouring Grout. This is know as a 'modified flitch' design and approximately doubles the stiffness of a typical timber, in bend.

Independent Engineering calculation service available, £150 per beam, Indemnified.

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New timber component in place - note bars in slots

Shear Connectors in Slots
Examples

Farmhouse, Crediton - understrength timber joists for proposed use as a first floor bedroom. These were slotted from above and Rebar bonded in using Structural Epoxy Pouring Grout.

Understrength floor timbers - awaiting upgrade from above

Understrength  Floor Beams


How to extend ends that have rotted

Cut out the decay and either:

1. Cut off the end completely and fit a Timber-Resin Splice, priced and manufactured to fit the exact size and timber type.

2. Build a box around the missing part, fit Rebars to extend into the sound part and fill with Structural Epoxy Pouring Grout.

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Timber-Resin Splice top slot (Type C) in place

Pouring Epoxy Resin
Examples

Bindon House Hotel, Somerset - truss ends and tie beams, Dry and Wet Rot. The ends were replaced using TYPE E Timber-Resin Splice units, made to measure .

Timber-Resin Splice Type E in place

Beam End Repair - Clerkenwell


How to prevent Timber damage

1. Protect structures from penetrating and rising dampness

2. Apply breathing protective coatings to external timbers - Vinabore

3. Treat vulnerable timbers with Boron Products - Boron Rods, Boron Paste, Boron Gel and Ultra 12 powder in water, by spray or brush for indoor use, to floor and roof timbers.

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Diagram of Boron Paste and Rod injection holes for a bearing end

Boron Paste & Rods in Joists
Examples

Ships - The Unicorn, Dundee, Wet and Dry rot

Castles - Dartmouth Castle, Taymouth Castle

Houses - The Log House, Bindon House

Pre-Treatment - 'Timborising', extensively used in New Zealand and Canada, 'green' timbers soaked in boric acid before drying and cutting to size

Drilling patterns for window cill preservation with Boron

 

For more help go to:

www.boron.org.uk - how to use Boron based insecticides/fungicides to treat timber rots and insect attack

www.dampness-info.co.uk - how to treat penetrating dampness in walls and plaster

www.deck-treatment.co.uk - how to treat patio decks and yacht decks

www.dryrot.biz - how to cure and prevent Dry Rot

www.epoxy-info.co.uk - epoxies, polyesters and polyurethanes for all applications

www.joist-repair.co.uk - how to quickly repair joists and beams of any size

www.timber.org.uk - systems of repair, with step by step methods

www.timber-repair.co.uk - how to repair timbers in buildings without wrecking the place

www.woodworm-info.co.uk - how to kill and prevent woodworm and death watch beetle

Boron Paste & Rods in Window Frames and Cills

Property Repair Systems
Unit 3, Olympus Business Park, Kingsteignton Road
Newton Abbot, Devon, TQ12 2SN
T: 01626 331351
F: 01626 331143
E: help@propertyrepairsystems.co.uk