
Which Backup Rod Size Fits Joints in Delhi Buildings
A 20 mm drawing dimension does not tell you which rod to order: the opening may be narrower at one point, wider at another, or partly blocked by old sealant. You will be able to measure the installed joint, apply a 25–50% oversize rule, select a practical polyethylene foam diameter, and set the rod to leave the correct sealant depth.
Key takeaways
- Measure joint width at several points, including the narrowest usable section.
- Choose a rod 25–50% larger than the measured joint width.
- Set sealant depth with the rod, not by forcing sealant into the full joint.
- Compare density, cell structure, compatibility, and test documents before ordering.
Measure the opening at its narrowest usable point
Measure the joint at its narrowest usable point before choosing a backup rod size for building joints in Delhi. Use a steel rule, vernier caliper, or joint-width gauge at the top, middle, and bottom, then repeat at several points along the façade, slab, window perimeter, or precast-panel run.
Record both the narrowest and widest readings; do not trust the nominal drawing width.


































