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DIY How To Tips

DIY Roofing

DIY roofing tips and information.

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How to Slate a Roof

Re-Slating Process

• Erect scaffolding for access and Health and Safety of roofers
• Strip and store existing slates - Random slates are sorted by length, size and thickness
• Re-felt the roof - Underlays are 'breathable membranes' which allow water vapour without air movement to move through and watertight and airtight to protect from rain and dirt blown between the slates and to protect against wind pressure on the underside of the slates.
• Re-batton to roof rafters using softwood cut to dimensions that prevent bounce when driving in the slate nails. Secured wood batton boards at each and at points along their length to a minimum of three rafters. Battons should be square sawn and butt-jointed at rafter centres, not spliced between supports or allowed to cantilever
• Re-slate - verge overhang, eaves up, overhang, top & ridge tiles. hole replacement slates to the correct gauge with the thicker end as the tail. The first course begins at the eaves and at the verges. Lay slates with broken bond up to the ridge, being aware of verges and abutments to reduce redressing or cutting of slates. Use thicker slates to the eaves and thinner to the ridge to minimise dead loading. Alternatively when creating a diminishing random effect use the smallest slates nearest to the ridge. Neighbouring slates are affixed with a 3-4 mm gap between them and two slanting slating nails that do not protrude above the face of the slate.
• Quality: position courses and laps along true and regular lines with slating nails that do not protrude above slate face. This allows overlying slates to sit snugly - so preventing wind chatter and reduced weather resistance. Ensure sufficient type of each slate before work begins. Remove debris to keep site and membranes clean. Keep mortar off slate face. Use patination oil on new leadwork.
• Re-fix lead flashings & chimney aprons
• Dry fix - replace any dry verges, hips, ridges
• Wet fix - verge pointing and fair ends - bedding and pointing of slates on gable ends and ridges with mortar

Nail and Bib Repair

• Identify the slate of slates that need replacing
• Use a 'slate ripper' that slides under the slate and hooks the retaining slate nail.
• Hit the 'slate ripper' on the handle to loosen the nail, and pull to extracted it.
• Remove the slate and match its characteristics with a replacement slate.
• Slide the replacement slate into place. Fasten it using a roofing nail in the slot between the two slates above it.
• Tap the roofing nail down and slide the bib flashing under the slate but over the nail head.

Slate Hook Repair

• Nail a copper or stainless steel hook in the slot between the under slates and if required push the hook into the slot.
• Slide the replacement slate in and over the hook.

DIY Problems

• Insecure fastening of slates so they blow off
• Poor selection of slate to match environmental characteristics of a site
• Poor selection of replacement slates so they don't blend with existing covering
• Selecting the wrong shape thickness or size of replacement slates
• Incorrect form of valley between roof sides
• Face nailed slates
• Tarred slates
• Using chipped or broken slates
• Using steel nails
• Weatherproofing chimney stacks with tar instead of lead

How to Slate/Tile/Flash A Roof Valley

Conical Slate Roofs

How to install flat slates onto a curved roof.

• Use 'shouldered slates' - with the corners cut off to allow them to sit without such obvious corners
• Felts applied and battened or ply base
• Insert an anchor point to the top of the turret and attach a line so the trimming lines can be set.
• To make it easy to align the slates on the curved roof lay as many slates as possible onto a straight board so the bottom edges align. Mark the outer slates and then snap a line across the slates to mark the bottom of the overlying course. This will ensure successive layers of overlaying slates are level.
• Set the overhang for the first slates with a measure, usually about 3 - 7 cm.
• Drill and screw in a cant strip or fascia board (cut into small strips to allow for curvature)
• Calculate the height and widths of the slates so they take account of the exposure area of each slate and head lap at the bottom.
• Use the anchor point line to snap mark a line. This is the correct angle up to the turret and trim the slate accordingly with a slate cutter. A slate can be used as a template for each course of slates. Slates ma then be cut out in advance and given a final trim at installation.
• Punch holes in the slates (from the slate back prior to trimming (to avoid wasted effort).
• Slates become progressively narrower towards the turret and atop the top wrung, a ridge of lead is often applied.
• Installation of a slate roof needs to be on top of structural materials with a similar lifespan
• Roofing contractors do not usually recommend use of plywood under slate as it can delaminate under adverse conditions.
• Use Thick rough sawn timber
• Never use galvanised nails, as their life span is usually less than slate. Copper or stainless steel nails should always be used.
• Always use adequate head lap.
• Always use appropriate tools for slate roofing to avoid wasted time and damage to the slates and roof.
• Use high quality (lead) flashings in the valleys and chimney aprons.

How to Choose a Roofing Contractor

• Know to the best of your ability what you want doing, how and by when.
• Many roofing contractors are not slaters or experienced in state roofing. Many do not conduct research into the techniques, material choices and tools to adequately quote and complete a job.
• Choose the appropriate quality slate for your location and roof type.
• Not all slates are top grades of Welsh and English slate. Some are imported and the lack of a UK standard can make comparison difficult.
• K-Roofing contractors are dedicated to finding the most appropriate slate for your new or refurbished roof. We understand the differences in slate specification grades and colour and will advise you honestly and accurately on the slate we believe will match your roof type, location and budget.
• Have a detailed contract
• Contract documents should specify details such as the type, size and origin of the slate to be used - its type, length and gauge of the nails; the type and installation style of underlayment; the type and size of cant strip; the head lap; flashing specifications; number of squares to be installed and slate installation style.
• Adequate head lap
• The head lap helps to protect your slates. Each slate must overlap 2 courses below it to maximise roof protection. Head lap is measured as the distance between the nail hole in a slate and area covered by the overlaying slate. To calculated the correct head lap: set the head lap required (often 7.5cm) and subtract this from slate length. Halve the remainder to give the exposed area.
• Poor flashings installation
• Use the correct Code rating for roof flashings for maximum weather and waterproofing service.
• Human traffic causing roof damage

• First slate - starter slate - upside down so beveled edges merge

Build Up Felt Flat Roof

How to Mend Cracked or Peeled Flat Roofs

The cause of cracks in felt roofs include where the bonded layers tear due to joint movement within the insulation, roof deck or roof structure. Roof design should allow for some differential movement. Once damage occurs, a simple DIY fix is to:

1. Ensure the damaged area is clean and dry
2. Identify the extent of the cracked felt and cut out this and any peeling felt using a strong, very sharp knife. To make the patch easier to make use a straight edge to cut a uniform shape.
3. The cut out piece is the template for replacement felt
4. You'll need a similar number to number of layers as those initially removed to ensure the roof is brought up to the same level
5. The top felt layer needs a larger area (about 5cm greater on each edge) to cover the patched area
6. In the damaged section, use a blunt knife to lift roofing cement under the lowest felt edges to create a watertight seal and a base
7. Cover the remainder of the base with roofing cement and apply the bottom felt patch into place. Secure with roofing nails. Subsequent layers do not require roofing cement, just roofing nails as the bond accommodates better minor movements which may have caused the initial crack
8. Apply the largest top patch over the 'damaged section' and nail it down, apply roofing cement around the edges to form a waterproof seal

Mending Blistered, Bubble Felt

Inadequately protected of the felt membrane from UV radiation generally causes blistering . Small blisters may form between the cap sheet and the underlay and are usually safe to leave, but need to be inspected periodically.

Blisters may also be caused by full bonding of layers when part bonding was required. Again, they might be left if intact. However, if a roof is to be overlaid then cut and reseal then.

1. Ensure the damaged area is clean and dry
2. Cut a straight line in the top layer
3. Lift and force roofing cement under the felt edges to make a watertight seal
4. Create a felt layer about 5cm greater on each edge to cover the patched area
5. Tack down using roofing nails
6. Create a larger top patch and nail it down.
7. Apply roofing cement around the edges to form a waterproof seal

Ponding

Ponding on a flat roof may become a problem if water can rise above the waterproof layer. Ponding may result from poor roof design, a roof structure that has deflected due to rotting of the timbers, or failure of the insulation or deck causing a depression.

K-Roofing investigates and assesses flat roof ponding problems and provides appropriate professional solutions to these.

Pitched Roofs

Leaking Roof

Sources of roof leaks can include:

• Water ingress through the membrane. If caused by a local, isolated membrane failure, repair holes, cracks, tears and splits. If a larger problem then an overlay may be required.
• Water ingress through associated roof details such as skylights, window flashings, copings, damaged or degraded rendering or damp courses. K-Roofing investigates and assesses flat roof ponding problems and provides appropriate professional solutions to these.

Roof Tiles

• Shaling is the splitting and crumbling of tiles caused by weathering. Evidence shows up as partial tiles and voids.
• Cracked tiles - tiles crack due to weathering and frost damage. Initially corners break off and work backwards which can allow water ingress into the roof.

Condensation

Condensation can cause problems within the roof structure, reduce heat retention and cause material degradation. Evidence of condensation may indicate:

• Poor or inadequate insulation between living space and membrane
• Excessive humidity in the living environment
• No of ventilation in a 'cold roof' - convert to a warm roof or add ventilation system
• Poorly sealed or inadequate vapour control layer - refit this layer, the saturated insulation and membrane