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Thin gap between window and lintel. Lead flashing visible above window from outside the flat.

Anonymous user 22 September 2015 - 9.55 PM

Dear Jason, Thank you for your reply. I should have clarified that the ventilation I referred to is for air to circulate around the brick walls. There is a trickle vent for room ventilation. A FENSA certificate is provided. So my question is this: Should that thin gap be sealed with mastic to prevent rain from blowing in or should it be left as it is, as any rain will just dry out by the air circulating. I checked all the other windows around the block and they all have this thin gap between window and lintel with visible lead flashing from the outside. I checked the NHBC website and in response to someone's question about the maximum gap for sealant around a UPVC window, their response was as follows. A gap should be allowed for thermal expansion of the window and it should be between 5-10mm. No mention whether it should be sealed. Thank you for your response. I must clarify that the thin gap between the window and lintel is visible only from the outside.

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