Base welding for profiles

About weld-on base plates for profiles

A base plate is welded to the bottom of a 40x40 mm railing post and is the part through which the post is anchored to a floor, slab or deck structure.

The plate area sets how widely the load spreads into the substrate, and how far from the post axis the anchor bolts can sit.

The Strofix range has four plate sizes for a 40x40 mm post – 80x80, 85x85, 100x100 and 105x105 mm.

All of these plates are supplied raw, because they are meant to be welded and then finished together with the seam. Do not look for a factory finish – it is applied after welding.

The choice depends on plate size, steel grade and whether the structure will be coated.

How to choose a weld-on base plate for a profile

1. Plate size (80x80 to 105x105 mm)

A larger plate spreads the load wider and lets the anchors sit further from the post axis, which lowers the pull-out force on each bolt.

A smaller plate is less visible and easier to conceal with a cover. Check the cover actually hides it – Strofix covers for profiles conceal plates up to 90x90 mm.

2. Steel grade: AISI 304, AISI 316 or S235

AISI 304 is the standard choice for interiors and normal outdoor exposure.

AISI 316 resists chlorides better and suits coastal sites and pool surrounds; in this range it covers the 85x85 and 105x105 mm plates.

S235 is carbon steel – only for structures that will be painted or galvanised after welding.

3. Welding and finishing

The plate is welded around the base of the post. On stainless steel the seam and the heat-affected zone must be cleaned after welding, or corrosion will start exactly there.

Apply the satin finish after the seam is dressed so the whole part reads as one surface.

4. Anchoring into the substrate

Choose the anchor type by substrate – chemical or mechanical anchors for concrete, coach screws for timber.

Use stainless fixings with a stainless plate; a galvanised bolt through a stainless plate outdoors sets up galvanic corrosion.