Can You Build a Deck Directly on Grass?

In Iceland, where frost heave is a significant concern, building a deck directly on grass is a recipe for disaster, according to landscape architect Björn Jóhannsson. His advice, published in Morgunblaðið, directly addresses a common shortcut that many homeowners might consider to save time and effort.

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Það er mjög dýrt að ætla að fara stystu leiðina í pallasmíði hér á landi. Ef þú leggur pallinn beint á grasið muntu fljótt lenda í tvennu: viðurinn fúnar vegna raka frá jarðveginum og frostlyfting mun skekkja allt mannvirkið.

Jóhannsson emphasizes that the unique challenges of the Icelandic climate, particularly the freeze-thaw cycles, mean that any structure resting on the ground without proper foundations will inevitably be compromised. The moisture from the soil will lead to rot, while the ground's movement will warp and destabilize the deck, rendering it unsafe and unsightly within a single winter.

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Íslenskur jarðvegur hreyfist mikið í frosti og pallur sem hvílir á grasi verður skakkur og skældur strax eftir fyrsta veturinn.

His recommendation is to invest in proper, frost-free foundations. This involves either replacing the soil with compacted gravel up to a depth of 70 cm or installing concrete posts that extend 90 cm below ground. By ensuring the deck's supports are below the frost line and allowing for adequate ventilation, homeowners can build a structure that will last for decades, a stark contrast to the short lifespan of a poorly constructed deck. This approach, while more labor-intensive initially, is presented as the only sensible long-term solution for building durable outdoor spaces in Iceland.

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Til að pallurinn haldist láréttur og endist, þarf að tryggja frostfríar undirstöður.