Using FenceFins is pretty straightforward. But we’ve compiled some FAQs we’ve received about posts, soil and other structures and we hope these answer any questions you have. We want to help you get it right every time so if you have a question that’s not here please use our contact form to get in touch and we’ll do our best to answer it (and add it to our FAQs).
FAQs – on posts and FenceFins
Q. What is the right size of posts for my fence?
A. Probably the most important of the FAQs to consider. It depends on the size of the fence:
- For a fence more than 6ft high or with posts more than 6ft apart use 4” x 4” posts.
- 3”x 3” posts are fine for fence ‘panel’ sizes less than 6ft x 6ft. However 4″x 4″ posts will make a sturdier fence that will last longer.
- For very exposed/windy sites, or ‘weak’ soil, (e.g. freshly disturbed, often wet or with high loam content) then we suggest 4”x 4” posts too.
- Remember you need posts 2ft (60cm) longer than the height of your fence because this length goes below ground.
Q. Can I use FenceFins on round posts?
A. Yes, FenceFins are available for 3” (75mm) round posts. Many people think round posts look much nicer than square posts for hurdle fences and screening made from willow, reed or similar. Please see our stockists pages for details.
Q. Can I use FenceFins on 3”x 4” posts?
A. Yes, if you overlap the FenceFins fully when you nail them on. To do this you will need to bend the FenceFins so they fit to the post. For example:
- For panel size less than 6’ x 6’ and using 3”x 3” FenceFins. Rebend the FenceFins to open them out so their ‘aperture’ is 4”. Then overlap them and nail to the 3” ‘faces’ of the post. Fix your panels to the 4” faces.
- If using 4”x 4” FenceFins, start by rebending them, closing down the aperture to 3”. Overlap them and nail them to the 4” ‘faces’ of the post. Fix your panels to the 3” faces.
Q. Can FenceFins be used with half round/half moon posts?
A. No, because they would only fit tightly on one side. This compromises the strength of the fitting.
Q. Can I use FenceFins on plastic/PVC posts?
A. Yes, they are ideal. Because plastic fence posts and FenceFins have a really long life and are so easy to maintain they work very well together. To fix them on we recommend 8 x 1” pan-head plated self-tapping Pozidrive screws
FAQs on installation
Q. What sort of nails do I need?
A. We recommend 3.75 x 30mm galvanised square twist nails. These are widely available from DIY stores, builders merchants and ironmongers.
Q. Can I use screws to fix the FenceFins to the post?
A. Yes, we recommend 8 x 1” pan-head plated self-tapping Pozidrive screws.
Q. How deep should the hole be?
A. At least 2ft (60cm) of post should go in the ground. The top edge of the FenceFins sits just below ground level so a hole depth of just over 2ft is needed. In our installation video here Andrew digs a little deeper and puts some rubble under the post. This helps with drainage and therefore prolongs the post’s life.
A quick tip – if you have a length of post about 2ft long, fix one set of FenceFins loosely to it (so you can remove them later). Use as a quick gauge for the depth and size of the hole (our thanks to Tyler, in San Francisco for this tip!).
FAQs on soil conditions
Q. How long will FenceFins last in damp ground?
A. FenceFins are made from galvanized steel so should last for several decades without rusting, even in damp ground. If the posts rot, the FenceFins can be removed and re-used.
Q. Are FenceFins suitable for boggy or very wet soil?
A. Anchoring any structure in very wet ground is challenging. Like other post anchors, FenceFins are subject to movement as the ground moves. However we would expect them to perform much better than spikes in such conditions and probably better than concrete, unless really large amounts of concrete are used. Even if the ground does move, with FenceFins it is easier to reset the post than if concrete is used.
Q. My soil is very rocky, will FenceFins work in that?
A. Yes, FenceFins should be very strong in this soil. If the gravel/rocks are more than around 1/2 inch (1 cm) in size then some ordinary soil or sand in your backfill will ensure the strongest results.
Q. How well do FenceFins cope with frost heave?
A. The movement of the soil caused by freeze/thaw can affect any fence anchor system, but FenceFins have a couple of advantages.
Firstly soil can pass up through the A-shape of the fin which minimises the ‘heave’ impact (see diagram to see how frost lenses push up a concrete fixing, or read more here).
Secondly, if displacement occurs a post with FenceFins you can reposition the post more easily once the ground thaws. Just loosen the post a little, perhaps dig out a little soil, adjust and re-compact the soil. Concrete or spikes, however, need much more digging out so are more difficult to maintain.
The risk of frost heave is reduced if there is good drainage around the post too.
FAQs on using FenceFins with other structures
Q. Can I use FenceFins to anchor my pergola/arbour?
A. This really is one of our most common FAQs, and the answer is that we generally don’t recommend it for a variety of reasons:
- Pergola with a roof: FenceFins are designed to resist wind forces on a fence or similar vertical plane surface (e.g. foliage on a trellis). They might not anchor enough against wind ‘lifting’ under a roof.
- Pergola without a roof: here you could use FenceFins but it will depend on the nature and weight of the structure. Please get in touch if you’d like more advice. Remember also if you are buying a pergola ready-assembled, or in kit form, the posts may not be long enough for 2ft (60cm) to go below ground.
Q. Can I use FenceFins to secure my sail shade?
A. No, we would not advise this. This is because FenceFins withstand lateral wind force on a fence (or similar) but not the force of the wind lifting upwards. With a sail shade much of the force of the wind is trying to lift the structure up and so pulling the post up out of the ground. We also advise against using metal spikes for the same reason, unless you angle them appropriately to resist both lateral and upward pull.