How the two differ in kind
Both members do the same job — take a concentrated load and carry it to a foundation — and both are limited by the same thing long before they are limited by their material's strength. A short stocky member fails by CRUSHING, at the strength of what it is made of. A tall slender one fails by BUCKLING, bowing sideways at a load well below that, and the buckling load contains no strength term at all: only stiffness, geometry and length.
The term that dominates is the effective length factor, which converts a real member into the equivalent pin-ended one the theory describes. It depends entirely on what restrains each end: fixed at both ends gives about a half, pinned at both gives one, and fixed at the base with a free top — a garden pier, a freestanding post — gives two. Because it is SQUARED, that range is about sixteen times in critical load for an identical member. Nothing else on this page moves the answer that far, and it is also the assumption most often taken optimistically, because a base that looks fixed rarely is.
Where they differ fundamentally is tension. Masonry has essentially none worth designing with: a pier resisting an overturning moment has a tension face, and the tension face cracks. That is why piers carrying lateral load are thick, or reinforced, or both, and why a slender decorative pier under a beam that also takes wind is a different problem from one under a pure vertical load. A timber post carries tension as readily as compression, so the same load case is unremarkable for it — and it fails instead at the base detail, where end grain meets water.
The factors that actually differ
Show
| Masonry pier | Timber post | |
|---|---|---|
| What limits it | Crushing when stocky; slenderness when tall. Codes commonly express the limit as a height-to-thickness ratio, which is buckling in disguise. | Buckling about its WEAKEST axis, unless something braces that axis. A post braced one way and not the other is two different columns. |
| Tension capacity | Effectively none. Any overturning produces a cracked face, which is why lateral load drives the size more than vertical load does. | Full. Uplift, wind and a beam that lifts at one end are all ordinary load cases. |
| Bulk for the load | Large. A pier that is slender enough to look elegant is often too slender to work without reinforcement. | Small. A timber post carrying a serious load is still something a person can lift. |
| The detail that decides its life | The damp-proof course and the cap. Water entering the top of a pier saturates it and freeze-thaw takes the face off. | The BASE. End grain in contact with a wet surface wicks water up the post, and the rot starts inside where nothing shows. |
| Load duration | Indifferent. Masonry's strength is not duration-dependent in any way that matters here. | Duration-dependent, and uniquely it goes UP for short loads — a post is stronger against a gust than against a permanently stacked load. |
| Speed and trade | A bricklayer, mortar and curing time. It cannot be loaded the day it is built. | Minutes, and loadable immediately. A carpenter, or nobody in particular. |
| Modifying it later | Hard. Cutting into a pier reduces its section where the cut is, and that is usually where the load is. | Easy, and dangerous for the same reason. Notching a post for a rail or a fixing removes far more capacity than material, because the notch is a crack initiator across the grain. |
| Appearance and context | Matches the building where the building is masonry, and reads as permanent. | Reads as lighter, and can be replaced without touching anything around it — which is an advantage a pier does not have. |
Which one, and when
Choose masonry pier when…
- The load is vertical and substantial, with no significant uplift or lateral push.
- The surroundings are masonry and a pier is what the building expects.
- The member is short relative to its thickness, so it is working in crushing rather than buckling.
- Permanence and low maintenance matter more than speed — a capped, damp-proofed pier is a very long-lived thing.
Choose timber post when…
- There is uplift or lateral load, where masonry's lack of tension capacity forces a much larger section.
- The member is tall and slender, where a timber post's stiffness-to-weight is far better.
- Speed matters and the load has to be carried immediately.
- It may need to be replaced one day — a post can be, and a pier essentially cannot.
Now run your own numbers
This page holds no prices on purpose — a national average is wrong for almost every real project. Quantify both options with your dimensions and your local quotes.
Frequently asked questions
- How slender is too slender?
- Expressed as a ratio rather than a dimension, and the limits in the codes are conservative stand-ins for a full buckling check. For masonry it is height-to-thickness, and the permitted value depends on what restrains the top — a pier propped by a beam that is itself braced is a very different member from a freestanding one, and the codes give different limits for each. For timber the ratio is effective length over radius of gyration, and the column stability factor blends the crushing and buckling limits empirically. In both cases the honest reading is that a ratio limit is a screening check you can perform on a drawing in seconds, at the price of conservatism and of saying nothing about the end conditions — which are the thing that actually decides it.
- Why does a brick pier have to be so fat?
- Two reasons compounding. First, slenderness: masonry's capacity falls sharply with height-to-thickness, so a tall pier needs thickness simply to avoid buckling, regardless of how modest the vertical load is. Second, and usually the binding one, tension. If the pier takes any lateral load — wind on a gate, a beam that lifts, a retaining action — the windward face goes into tension, and masonry has no useful tension capacity. The only things resisting that are the pier's own weight and its width, so the section grows until the compression from self-weight keeps the whole face in compression. That is why a decorative pier that looks right is so often a reinforced one with a bar down the middle of a grouted core.
- Can a timber post sit directly on concrete?
- Not on its end grain, not if it is meant to last. Concrete is porous and holds water, end grain wicks it enthusiastically, and the rot starts inside the post where nothing is visible until the post is soft. The standard detail lifts the post clear on a metal base or shoe that keeps end grain out of contact and lets air reach all faces — and that gap is not cosmetic, it is the whole mechanism. Where a post is set INTO concrete the same logic applies more severely: the concrete holds water against the buried timber and the post rots at ground level, which is exactly where the bending moment from any lateral load is greatest. Preservative treatment helps and does not substitute for the detail, particularly at a cut end, which exposes untreated timber.
- Does mortar strength decide a pier's capacity?
- Less than most people expect. Masonry compressive strength is dominated by the unit strength and by the slenderness of the member, with mortar contributing but not governing across the ordinary range — and a stronger mortar is not automatically better, because a mortar stiffer than its units transfers cracking into the bricks rather than accommodating movement in the joints. That is why conservation practice specifies weaker lime mortars for soft historic units: the joint is meant to be the sacrificial element. The place mortar strength does matter is bond, which is a tension property, and there the governing variable is not the mix at all but whether the units were wetted, as the masonry methodology sets out.
- What does a notch do to a timber post?
- Much more than remove material, and the reason is grain direction. A notch creates a sharp re-entrant corner, and at that corner tension develops ACROSS the grain — the direction in which wood is an order of magnitude weakest. A crack starts there and then runs ALONG the grain, splitting the member far beyond the notch itself. So the loss of capacity is out of proportion to the section removed and does not scale smoothly with notch depth, which is why the rules are geometric limits and permitted zones rather than a stress calculation. A round hole is far more benign than a notch of the same depth, because it has no sharp corner to start the crack.
- Should I just use a steel post?
- Often, and it is a fair question to put to both. Steel is slender, strong in both directions, carries tension, and can be fixed with a designed baseplate that gives genuine restraint rather than an assumed one. What it brings is corrosion protection to maintain, a colder surface where it passes through an insulated envelope, and — for the same reason as a timber post — a base detail that must keep it out of standing water. Where a pier is being made large purely to resist a modest lateral load, a steel post with a proper base is frequently the smaller, cheaper and more honest answer, and the pier is then a decorative casing around it rather than the structure.