Repair Rafters

How to repair wooden rafters in a roof

Property Repair Systems - 01626 331351 - speak to real people about resin repair of structural timber

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How to repair timber Rafters

This project is presented by Property Repair Systems. We show you how to make Structural repairs to Rafters inside roof spaces without destroying sound timber or opening the roof.

Definition of a Rafter

"a sloping beam supporting a roof" (Definitions may vary regionally, as may the spelling)

Rafters connect the roof ridge down to the wall. The large ones are called 'Principal Rafters', the smaller, more numerous ones are called 'Common Rafters'.

Broken Rafter, caused by insect attack in a thatched roof

Typical Rafter - badly broken, insect attack

Common Location in Buildings

Roofs - sloping from the ridge down to the walls - they often sit on the walls on 'Wall Plates' made of wood, which also rot.

Decay causes

Roof leaks - valley leaks, blocked or damaged gutters and downpipes.

Wet rot and insect attack then destroy the bearing ends.

Valley gutter failure in a roof truss leading to wet rot

Wet rot in a Tie Beam and Rafter from a valley leak

Dry rot in a Tie Beam end, shows cubing

Dry rot in a Rafter end - note the cubing effect

Other Factors often seen on Survey

Internal spread of rot along the grain - decay may extend a long way up the rafter from the tie beam

Drilling a large Tie Beam to check for the extent of rot

Drill testing reveals the extent of decay - use a Auger

 


Information required from Survey of a Rafter

Access for Repair - usually from the side face

Note - check any neighboring properties for similar decay through the Party Wall, where there may be a hidden Valley. Compression during rotting often causes cracking to external render.

Size - width, depth, length, bearing support length

Number - more than one may be affected, check both sides of the roof and the wall plate

Timber type - softwood (Pine) or hardwood (Oak), not known

Decay type - wet rot, insect attack (CFB, DWB or Longhorn), Dry rot

Amount to cut off - drill test holes if possible, or tap with a hammer

Final appearance required - visible but painted, decorative natural finish, hidden

Handed - a sketch is useful, with dimensions

Tie Beam - may be affected as well, note the size and method of attachment


Repair Options for Rafters

Repair Types - solid resin or Timber Resin Splice (TRS)

Most popular access Types - side slot, bottom slot - in order to leave the roof intact

TRS Types - Side Slot = Type D, Bottom Slot = Inverted Type C

Special situation - mid span damage - use a doubled ended TRS with a connection at both ends..


Photo Gallery for Truss Repairs by TRS Type

Type A - Solid Epoxy Resin - removable shuttering - drilling up the end grain of the Parent timber on Site

Type B - Solid Epoxy Resin - permanent shuttering - drilling up the end grain of the Parent Timber on Site

Type C - Timber Resin Splice supplied with fitted bars - Top Slot(s) in the Parent timber.

Type D - Timber Resin Splice supplied with fitted bars - Side Slot(s) in the Parent timber

Type E - Timber Resin Splice supplied with Top Slot(s) - drill holes up the end grain of the Parent timber.

Type F - Timber Resin Splice supplied with Side Slot(s) - drill holes up the end grain of the Parent timber.

Type G - Timber Resin Splice supplied with Top Slot(s) - cut Top Slot(s) in the Parent timber.

Type H - Timber Resin Splice supplied with Side Slot(s) - cut Side Slot(s) in the Parent timber.


Heritage Considerations for repairing Rafters

Repair Type - a Conservation Officer will generally prefer a Timber Resin Splice over a Solid Resin Repair

Timber Resin Splice Side Slot Type D in a rafter

Timber Resin Splice Type D Side Slot in a rafter

TRS Type - a Conservation Officer will generally prefer least damage to the parent timber, so TRS Types E (Top Slot) and F (Side Slot) may be offered, in which the slots are created during Manufacture in the new timber and the Technician drills holes up the end grain of the Parent. This is only feasible if the cut off length is at least 600mm.

TRS Type E - cut off the rotten endTRS Type E - drill holes up the end for bars to be bonded intoTRS TYpe E - bars bonded into place

TRS Type E - TRS in place, open top slot or slotsTRS Type E - pouring Structural epoxy Resin into the top slot

TRS Type E Steps - Technician has to drill up the end grain, so needs good clearance to the wall.


More unusual Timber Resin Repair types

Mouldings - sometimes found on the visible decorative faces or edges of Rafters exposed in a room

Connectors - at the joint between the rafter and the tie beam - may have to be restored as original - or use our Tie Connector Kit.

Glulams - can be used as Rafters and Tie Beams.


Structural Calculations for Repairing Rafters

Free of charge - our Design and a Check Calculation - not Insurance Indemnified - we are not Structural Engineers - same day service

Chargeable - independent Structural Engineer - ask for one of our Forms - Indemnified by a Qualified Structural Engineer - allow at least 5 working days.

Tie Structural Data Collection Form - click here for the Form used when we submit your Beam Repair to a Structural engineer.


Epoxy Resins for Repairing Rafters

To buy resins - visit our Resins Shop

Sealing beam end face to a TRS or to seal Shutter Boxes - Quick Setting Wood Filler

Pouring into Shutter Boxes (Type A or Type B) and Top Slots (Type C, E) - Structural Epoxy Pouring Grout

Injecting into Side Slots (Type D and Type F) - Structural Epoxy Pouring Grout plus 1 litre Cartridges and Skeleton Gun

Bonding Bars into timbers on site - for Solid Resin Repairs, Type A and Type B and TRS Timber Kits Type E and Type F - Thixotropic Epoxy Injection Resin plus 400cc Cartridge Kits and Skeleton Gun, with extension tubes for the Cartridges.


Bars used for Repairing Rafters

Bars fitted to TRS Units - Zinc Plated High Tensile Grade 8.8 Steel Allthread

Couplers - available for joining threaded bars in some applications

Bars fitted on Site - either Zinc Plated High Tensile Grade 8.8 Steel Allthread or Epoxy-Glass Bar


Types of Wood used for Timber Resin Splice Rafter Repair Kits

Standard Kiln Dried Softwood (Pine) - white or Redwood Pines, Strength Graded C24

Non standard Kiln Dried Softwood (Southern Yellow Pine, Douglas Fir) - yellow or red striped Pines, Strength Graded C24

Non standard Kiln Dried Hardwood (Oak) - English or American Oaks, not Strength Graded

Non standard Air Dried Hardwood (Oak) - English Oak, will contain insect holes, shakes and splits, will not be dimensionally stable, may shrink, twist and split further in service.


Special Tools for Repairing Rafters - we hire these tools

Cutting Slots - Low Speed, High Torque , reversible electric drilling machine (minimum power - 1000 watts), in conjunction with fully fluted wood Augers

Drilling Holes up the ends of beams - Low Speed, High Torque , reversible electric drilling machine (minimum power - 1000 watts), in conjunction with fully fluted wood Augers

Injecting into Side Slots (Type D and Type F) - 1 litre Skeleton Gun

Bonding Bars into timbers on site - for Solid Resin Repairs, Type A and Type B and TRS Timber Kits Type E and Type F - 400cc Skeleton Gun


Manufacturing Time for Timber Resin Splice Rafter Repair Kits - minimum

Made in standard Kiln Dried Softwood (Pine) - 3 working days, plus 2 working days for delivery

Made in non standard Kiln Dried Softwood (Southern Yellow Pine, Douglas Fir) - 5 working days, plus 2 working days for delivery

Made in non standard Kiln Dried Hardwood (Oak) - 7 working days, plus 2 working days for delivery

Made in non standard Air Dried Hardwood (Oak) - 21 working days, plus 2 working days for delivery

Elm is also available to Special Order - expensive.


Drawings of installation steps for Timber Resin Splice Rafter Repair Kits

Type A - Solid Epoxy Resin - removable shuttering - drilling up the end grain of the Parent timber on Site

Type B - Solid Epoxy Resin - permanent shuttering - drilling up the end grain of the Parent Timber on Site

Type C - Timber Resin Splice supplied with fitted bars - Top Slot(s) in the Parent timber.

Type D - Timber Resin Splice supplied with fitted bars - Side Slot(s) in the Parent timber

Type E - Timber Resin Splice supplied with Top Slot(s) - drill holes up the end grain of the Parent timber.

Type F - Timber Resin Splice supplied with Side Slot(s) - drill holes up the end grain of the Parent timber.

Type G - Timber Resin Splice supplied with Top Slot(s) - cut Top Slot(s) in the Parent timber.

Type H - Timber Resin Splice supplied with Side Slot(s) - cut Side Slot(s) in the Parent timber.


Method Statements for Timber Resin Splice Rafter Kits

Type A - Solid Epoxy Resin - removable shuttering - drilling up the end grain of the Parent timber on Site

Type B - Solid Epoxy Resin - permanent shuttering - drilling up the end grain of the Parent Timber on Site

Type A and B Modified - Solid Epoxy Resin - side slots in the Parent Timber due to lack of cutoff space to end drill

Type C - Timber Resin Splice supplied with fitted bars - Top Slot(s) in the Parent timber.

Type D - Timber Resin Splice supplied with fitted bars - Side Slot(s) in the Parent timber

Type E - Timber Resin Splice supplied with Top Slot(s) - drill holes up the end grain of the Parent timber.

Type F - Timber Resin Splice supplied with Side Slot(s) - drill holes up the end grain of the Parent timber.

Type G - Timber Resin Splice supplied with Top Slot(s) - cut Top Slot(s) in the Parent timber.

Type H - Timber Resin Splice supplied with Side Slot(s) - cut Side Slot(s) in the Parent timber.


Download Data Sheets and Safety Data Sheets for Resins

Structural Epoxy Pouring Resin and Grout - for pouring into slots and into cartridge tubes for injection - Data Sheet - Safety Data - Activator

Safety Data - Base - Safety Data - Powder

Thixotropic Epoxy Injection Resin - for injecting holes using 400cc cartridge tubes - Data Sheet - Safety Data Sheet Activator - Safety Data Sheet Base

Mouldable Epoxy Putty - for filling defects - Data Sheet - Safety Data Sheet


Where to find more reading and photographs of Timber Resin Repairs

www.timber-repair.co.uk - how to repair timber beams

Timber Repair Review 1 - Timber Repair Review 2 - call us for the printed versions - 01626 331351

TRADA Eurocode - resin repair technical report by the Timber Research and Development Association

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


Timber Decay Links for photographs of rots and insect damage

www.dryrot.biz - how to kill Dry Rot in buildings

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

www.woodworm-expert-advice-forum.org.uk - all your questions and our answers about woodworm damage and treatment


Technical Help for repairing Rafters

Property Repair Systems expert staff can help you with all kinds of timber repairs and are more than happy to give further information and advice.

Call 01626 331351 or E: Mail us help@propertyrepairsystems.co.uk


Timber Beam Repairs | Contact | About Us | About the Author | Index Page


 

Property Repair Systems

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Site written by: David Moore

David Moore, B.A. (Hons.), C.T.I.S., C.R.D.S. Technical Author

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www.fire-door-paint.co.uk - upgrade doors to 30 minutes fire resistance

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

www.propertyrepairsystems.co.uk - our Home Site

www.steel-fire-paint.co.uk - treat steel with Intumescent Paint to provide fire protection

www.timber-repair.co.uk - how to repair timber beams

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

www.woodworm-expert-advice-forum.org.uk - all your questions and our answers about woodworm treatment DIY