Slotted vs Morticed Concrete Posts: Which Do You Need?

The main difference between slotted and morticed concrete posts is how the fencing is held in place. Slotted posts have a continuous channel that accepts a complete fence panel. Morticed posts have shaped holes for horizontal rails, which support individual feather edge boards or other closeboard components.

Both types provide a strong, long-lasting alternative to timber posts, but they are not normally interchangeable within the same fence run. Your choice determines which panels, rails, gravel boards and fittings you will need.

What are slotted concrete posts?

Slotted concrete posts have a groove running down each side. A complete fence panel slides between two posts, with the panel edges sitting inside the grooves. This creates a straightforward post-and-panel system that is popular in gardens, along boundaries and for replacing storm-damaged fencing.

You will usually use slotted posts with standard-width timber panels. Depending on the chosen design, these may include waney lap, closeboard, decorative or other framed panels. Browse our fence panels alongside the available post sizes before ordering.

A typical run uses an intermediate slotted post between each pair of panels. At the end of a run, you can use an end post with a slot on one side. Corner posts have slots positioned to take panels in two directions. Choosing the correct post shape makes the fence neater and avoids relying on unsuitable fixings.

How panels fit into slotted posts

The posts are set at the correct centres for the width of the panels. Once the concrete has cured and the posts are stable, each panel is lowered vertically into the slots. A gravel board can sit below the panel to keep the timber away from damp ground.

Because the panel is held within the channels, it generally does not need to be screwed directly to the concrete. Panels can also be removed and replaced more easily than individual closeboard components, provided there is enough space to lift them out.

What are morticed concrete posts?

Morticed concrete posts are designed for traditional closeboard fencing built from separate components. Instead of continuous channels, each post has rectangular holes called mortices. The shaped ends of horizontal rails fit into these holes, creating the framework for the fence.

Vertical feather edge boards are then fixed to the rails, usually overlapping one another to form a solid screen. A timber or concrete gravel board is fitted at the bottom. This method lets you build the fence board by board rather than placing a ready-made panel between the posts.

As with slotted posts, there are different morticed post configurations. Intermediate posts accept rails from both sides along a straight run. End posts finish a run, while corner posts allow the fence to change direction. You must also match the number and position of the mortices to your planned fence height and rail arrangement.

How rails fit into morticed posts

Closeboard rails have ends shaped to sit inside the mortices. During construction, the rails are positioned between the posts so that their ends are securely supported. The feather edge boards are then fixed to the rail faces.

This system does not take ordinary framed fence panels. If you already have standard panels or want panels that can be replaced as complete units, slotted posts are normally the appropriate choice. If you want a continuous closeboard fence assembled on site, morticed posts are usually required.

Slotted vs morticed concrete posts at a glance

• Slotted posts: Designed to hold complete framed fence panels in vertical grooves.
• Morticed posts: Designed to hold horizontal closeboard rails in shaped holes.
• Slotted system: Usually faster and simpler for a standard post-and-panel boundary.
• Morticed system: Allows you to construct continuous closeboard fencing from rails and individual boards.
• Panel replacement: A damaged panel can generally be removed as one unit from slotted posts.
• Local adjustment: Individual feather edge boards on a morticed system can be replaced without changing a complete panel.
• Appearance: Slotted systems show framed panel sections, while morticed closeboard fencing has a more continuous board-by-board finish.

Neither option is automatically better. The right product is the one designed for your fencing material and the result you want.

When should you use slotted concrete posts?

Choose slotted posts when you are using ready-made fence panels. They are particularly practical when you want a familiar garden fence layout, a choice of panel styles or a system that makes future panel replacement manageable.

Slotted concrete posts also work well with compatible concrete gravel boards. These boards sit between the posts beneath the timber panel, helping to protect it from soil contact, moisture and damage from garden maintenance. You can view our gravel boards when planning the complete bay.

Remember that decorative panels can vary in height, frame thickness and construction. Check that your selected panel is suitable for the post slots and that the total height of the panel and gravel board matches your post length and intended finished height.

When should you use morticed concrete posts?

Morticed posts are the usual choice when you want a traditional closeboard fence built using arris rails and feather edge boards. This type of construction is useful for long boundaries and situations where you prefer the appearance of continuous vertical boarding.

Building board by board can also give you some flexibility around non-standard sections, but the rail spacing, post centres and board quantities need careful planning. The components must be compatible: the rail ends need to match the post mortices, and the post must have the correct number of mortices for the fence design.

If you are repairing an existing closeboard run, inspect the current posts before ordering. A post may look similar from a distance but have different mortice dimensions or spacing. Measuring accurately helps you avoid ordering rails that will not fit.

What should you measure before ordering?

Start by measuring the total boundary length and noting every corner, end, gate opening and change in level. Then decide whether you are buying complete panels or constructing closeboard fencing from separate boards and rails.

• For slotted posts: Check panel width, panel height, frame thickness, gravel board height and the required post length.
• For morticed posts: Check post centres, rail type, rail size, number of rails, mortice position, board height and gravel board type.
• For both systems: Count intermediate, end and corner posts separately rather than treating every post as identical.
• For gates: Plan gate posts and openings independently, as a gate creates different loads from a fence panel.
• For sloping ground: Decide whether the fence will step down in sections and allow for the resulting height changes.

Concrete posts are heavy, so handling and access also matter. Think about how materials will reach the boundary, whether there are steps or narrow passages, and where they can be stored safely before the work begins.

Common ordering mistakes to avoid

One common mistake is buying slotted posts for loose feather edge boards and rails. Without suitable mortices, the rails do not form the intended closeboard framework. The reverse mistake is ordering morticed posts for complete framed panels, which cannot simply slide into place.

Another issue is forgetting the gravel board when calculating post length. A fence made from a panel above a gravel board needs enough post length for the finished above-ground height and a secure section below ground.

Do not assume that every straight run uses only intermediate posts. You may need purpose-made end or corner posts. It is also sensible to check sizes across all components rather than mixing products based only on their stated fence height. Our concrete posts range can help you identify the appropriate type.

Order concrete posts from K C Fencing and Timber Ltd

K C Fencing and Timber Ltd manufactures and supplies fencing materials for trade and DIY customers across the West Midlands. We offer delivery across the region, including Wolverhampton, Birmingham, Walsall, Dudley, West Bromwich, Wednesbury, Worcester, Redditch, Stourbridge, Kidderminster and Halesowen. Free collection is available from our yard at 83 Portway Road, Wednesbury WS10 7DZ.

If you are unsure about slotted vs morticed concrete posts, call 01902 288162 with your measurements and planned fence type, or request a quote. We can help you choose compatible posts, panels, rails and gravel boards for your project.