Siding installation on walls that have never been clad

What is siding installation for new builds & additions?

This page covers siding installation on new construction and additions - walls with no existing cladding to remove. If you are re-cladding an existing house, that is a different job with a different risk profile, and it is covered on our siding replacement page. On a new wall the sheathing is sound and visible, so nothing gets discovered mid-project. What matters instead is sequence: the water-resistive barrier, the flashings and the trim have to go on in the right order, and every mistake is buried behind the finished wall.

Signs you need siding installation for new builds & additions

• You are building an addition and the new wall has to tie into existing cladding that may be faded or a discontinued profile
• You are finishing a new build and the builder’s allowance covers a base material you want to upgrade from
• You are cladding a garage conversion, a dormer, a porch enclosure or an outbuilding
• A wall has been left with only house wrap exposed to the weather for months, which most barriers are only rated to tolerate for a limited period
• You are adding continuous exterior insulation and the siding has to be detailed over it - a different fastening and trim problem from a plain wall

Seeing something not on this list? Browse siding problems by symptom →

How siding installation for new builds & additions actually works

1. 1

   Sheathing check and the tie-in plan

   Confirm the sheathing is dry, flat and fastened, and - on an addition - plan how the new wall meets the old. Matching an existing profile and colour on an addition is the same problem repair work faces, and it is far cheaper to solve at design stage than after the panels arrive.

   Watch forCladding installed over sheathing that got wet during framing and was never allowed to dry. Trapping moisture behind a new wall on day one is an unforced error.

2. 2

   Water-resistive barrier, lapped shingle-style

   House wrap or building paper goes on with every upper course overlapping the one below, so gravity carries water down and out rather than into a lap. Seams are taped or lapped to the manufacturer’s spec, and the barrier runs behind - not butted to - window and door openings.

   Watch forAn upper course tucked behind a lower one. It is the most common and most consequential error in the whole job, it is invisible once the siding is on, and it turns your barrier into a funnel. You can check this yourself before cladding starts.

3. 3

   Flashing at openings and penetrations

   Sill pans under windows, head flashing above every opening, kick-out flashing where a roof edge dies into a wall, and proper blocks or hoods at every vent, hose bib, light and electrical box.

   Watch forKick-out flashing left off at a roof-to-wall junction. It is a small, cheap piece of metal, its absence dumps a roof’s worth of water into one spot of wall, and it is one of the most common causes of concealed rot in newer homes.

4. 4

   Furring and rainscreen, where it applies

   Some assemblies - and some climates and some materials - call for a drainage gap between the barrier and the cladding, created with furring strips or a drainage mat. It lets any water that gets behind the siding drain and dry.

   Watch forA rainscreen specified in the drawings and quietly omitted on site. In wet climates it is the difference between a wall that dries and one that does not, and it cannot be added later.

5. 5

   Starter strip, corners and trim first

   Trim goes on before the field of the wall: corner posts, J-channel at openings, and a starter strip set dead level. The starter determines the line of every course above it, so a starter that is out is a wall that is out.

   Watch forA starter strip levelled off the foundation or the ground rather than with a level or a laser. Foundations are not level, and the error compounds visibly up the wall.

6. 6

   Hanging the cladding with movement allowed for

   Each material has published requirements for fastener type, spacing, penetration depth and clearance at openings. Vinyl is hung rather than fixed - nailed in the centre of the slot with the head left slightly proud so the panel can slide.

   Watch forPanels nailed tight, nailed off-centre in the slot, or butted hard against trim with no clearance. All three void most warranties, and all three produce the wavy wall that appears in the first hot week and never goes away.

7. 7

   Cut ends, joints and finishing

   On fiber cement and wood, every field cut exposes raw material and needs priming or sealing. Butt joints get flashing or a joiner, and the gap and sealant detail follows the manufacturer’s instruction rather than local habit.

   Watch forUnprimed cut ends. It takes seconds and is the origin of most premature edge swelling and paint failure on fiber cement and engineered wood.

What does siding installation for new builds & additions cost?

New-build and addition cladding is normally priced per square foot of wall installed, and the material choice moves it far more than the labour does. Storey height, corner count, trim linear footage and any rainscreen or exterior insulation detail are the other drivers. The cost guide covers each material.

See the full siding installation for new builds & additions cost guide - by material, size and region →

If the number is the problem, here are the ways people pay for it →