Macro and microstructural damage was studied in typical glass fibre-reinforced polymer laminates with two types of coating systems – (a) isophtalic gel coat: pure or mixed with SiO₂ nanoparticles 5 wt% (5%N) or 10 wt% (10%N) and (b) a two-layer coating system: urethane-modified vinyl ester-based gel coat and additional polyester barrier coat layer. Accelerated tests were performed at 50°C for 50 days for specimens with nanoparticle-modified gel and for the specimens with or without a barrier coat. Long-term ageing behaviour at 23°C was assessed for the two-layer systems. Nanoparticle-reinforced specimens (10%) showed some advantage over ‘barrier coat systems' in terms of blister incubation time (16 and 13 days, respectively), while for 5% and 0% nanoparticles, blister incubation times were 3 and 7 days, respectively. Round and/or acicular blisters were observed on the examined surfaces. The varying size, shape and distribution of blisters was illustrated by macro and micrographs showing various failure modes associated with surface blisters.