Reduces breakage
By providing a slim, well-supported separation between roof slates, SlateSpacer™ reduces point loading, a leading cause of slate breakage. Walk testing shows that SlateSpacer™ supports heavy loads under challenging conditions.
Walk testing
Walk testing* shows that SlateSpacer™ supports slate well, even under challenging conditions:
- Workman's weight: 91Kg (200 pounds)
- Weight placement: concentrated on one foot on the slate's exposed end (including the corners)
- Slate thickness 4 mm (less than 3/16")
Furthermore, SlateSpacer™ reduces breakage from improper nailing.
SlateSpacer™ reduces breakage from proud nail heads (fig. 1).
Proud nail heads are one of the leading causes of slate failure. They can result from inattention or from a wish to avoid over-driving nails. Sometimes countersinks are insufficient to permit nails from being driven flush with the slate's surface (fig. 2). By separating slates, SlateSpacer™ has the effect of providing generous countersinks, increasing the margin for error (fig 3).
Spacers provide 30X more effective support than nail heads. Nail heads can break slates; SlateSpacer™ does not.
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fig. 1 |
fig. 2 |
fig. 3 |
SlateSpacer™ supports slates where they most need it.
SlateSpacer™ sits under the slate's exposed end, the part that receives the most direct loading.
SlateSpacer™ gaps are thinner than existing gaps.
Inherent, natural variances in slate thickness create widespread, intermittent gapping in virtually all slate roofs. Even sorting does not eliminate gapping. When a thin slate is beside a thicker slate, half the overlying slate projects, unsupported, over the thinner slate. Thickness variances commonly present 2 mm (slightly less than 1/8") gaps; in some markets, these gaps are considerably larger. The gaps that SlateSpacer™ presents are approximately half those that occur naturally (1.2 mm (less than 1/16")).
*The usual precautions apply
In many markets, installers are cautioned to avoid walking directly on roof slates. They are taught to spread foot loads by walking on planks or ladders laid across the slates. This remains sound advice. With or without spacers, walking on slates involves risk. Unbeknownst to the roof walker, slates may be too thin, or they may be cracked. Decks (support surfaces) may be uneven, and nails may be significantly over or under-driven. All of these conditions can predispose slates to break, to give way, and to increase the risk of injury.