diff --git a/src/kiri/mode/sla/work/init-work.js b/src/kiri/mode/sla/work/init-work.js
index 86eacd09..8a93e90c 100644
--- a/src/kiri/mode/sla/work/init-work.js
+++ b/src/kiri/mode/sla/work/init-work.js
@@ -20,6 +20,27 @@ function init(worker) {
     // console.log({ INIT_SLA: worker });
 }
 
+export function ensureSLAMemory(required) {
+    let wasm = SLA.wasm;
+    let available = wasm.memory.buffer.byteLength;
+
+    if (available >= required) {
+        return;
+    }
+
+    let page = 65536;
+    let pages = Math.ceil((required - available) / page);
+    try {
+        wasm.memory.grow(pages);
+    } catch (error) {
+        let growError = new Error(`SLA WASM memory grow failed: need ${required} bytes, have ${available} bytes`);
+        growError.code = "SLA_WASM_MEMORY";
+        growError.cause = error;
+        throw growError;
+    }
+    wasm.heap = new Uint8Array(wasm.memory.buffer);
+}
+
 // runs in worker. would usually be in src/mode/sla/prepare.js
 // but the SLA driver skips the prepare step because there is no path routing
 async function sla_prepare(widgets, settings, update) {
diff --git a/src/kiri/mode/sla/work/raster.js b/src/kiri/mode/sla/work/raster.js
index 4b2e43ee..fc85afb5 100644
--- a/src/kiri/mode/sla/work/raster.js
+++ b/src/kiri/mode/sla/work/raster.js
@@ -30,9 +30,10 @@ export function renderRasterLayers(print, renderer, onlayer, progress) {
     let { process, widgets, width, height, scaleX, scaleY, layermax } = ctx;
     let volume = 0;
     let count = 0;
+    let useWasm = renderer.renderLayerWasm !== undefined;
 
     for (let index=0; index<layermax; index++) {
-        let rendered = renderer.renderLayerWasm({
+        let params = {
             index,
             width,
             height,
@@ -40,7 +41,22 @@ export function renderRasterLayers(print, renderer, onlayer, progress) {
             scaleX,
             scaleY,
             masks: []
-        });
+        };
+        let rendered;
+
+        if (useWasm) {
+            try {
+                rendered = renderer.renderLayerWasm(params);
+            } catch (error) {
+                if (error.code !== "SLA_WASM_MEMORY" || !renderer.renderLayer) {
+                    throw error;
+                }
+                useWasm = false;
+            }
+        }
+        if (!useWasm) {
+            rendered = renderer.renderLayer(params);
+        }
         if (rendered.end) break;
 
         volume += rendered.area * process.slaSlice;
diff --git a/src/kiri/mode/sla/work/x_cxdlp.js b/src/kiri/mode/sla/work/x_cxdlp.js
index b653503a..793947cf 100644
--- a/src/kiri/mode/sla/work/x_cxdlp.js
+++ b/src/kiri/mode/sla/work/x_cxdlp.js
@@ -1,6 +1,6 @@
 /** Copyright Stewart Allen <sa@grid.space> -- All Rights Reserved */
 
-import { SLA } from './init-work.js';
+import { SLA, ensureSLAMemory } from './init-work.js';
 
 const default_values = {
     magic1: 'CXSW3DV2',
@@ -394,8 +394,11 @@ CXDLP.render = function(params) {
         }
     });
 
-    let wasm = SLA.wasm;
     let imagelen = width * height;
+    let metadata = 6 + array.reduce((total, poly) => total + polyRecordBytes(poly), 0);
+    ensureSLAMemory(imagelen + metadata + 1024);
+
+    let wasm = SLA.wasm;
     let writer = new self.DataWriter(new DataView(wasm.memory.buffer), imagelen);
     writer.writeU16(width, true);
     writer.writeU16(height, true);
@@ -431,3 +434,13 @@ CXDLP.render = function(params) {
     }
     return { lines, area };
 }
+
+function polyRecordBytes(poly) {
+    let bytes = 14 + poly.points.length * 8;
+    if (poly.inner) {
+        for (let i=0, il=poly.inner.length; i<il; i++) {
+            bytes += polyRecordBytes(poly.inner[i]);
+        }
+    }
+    return bytes;
+}
diff --git a/src/kiri/mode/sla/work/x_photon.js b/src/kiri/mode/sla/work/x_photon.js
index 67af34ea..0fce6625 100644
--- a/src/kiri/mode/sla/work/x_photon.js
+++ b/src/kiri/mode/sla/work/x_photon.js
@@ -1,6 +1,6 @@
 /** Copyright Stewart Allen <sa@grid.space> -- All Rights Reserved */
 
-import { SLA } from './init-work.js';
+import { SLA, ensureSLAMemory } from './init-work.js';
 
 function generatePhoton(print, conf, progress) {
     let printset = print.settings,
@@ -445,8 +445,12 @@ function renderLayerWasm(params) {
         }
     });
 
-    let wasm = SLA.wasm;
     let imagelen = width * height;
+    let metadata = 6 + array.reduce((total, poly) => total + polyRecordBytes(poly), 0);
+    let rleSpace = masks.length ? imagelen : 0;
+    ensureSLAMemory(imagelen + Math.max(metadata, rleSpace) + 1024);
+
+    let wasm = SLA.wasm;
     let writer = new self.DataWriter(new DataView(wasm.memory.buffer), imagelen);
     writer.writeU16(width, true);
     writer.writeU16(height, true);
@@ -471,6 +475,16 @@ function renderLayerWasm(params) {
     return { image, layers, end: count === 0, area };
 }
 
+function polyRecordBytes(poly) {
+    let bytes = 14 + poly.points.length * 8;
+    if (poly.inner) {
+        for (let i=0, il=poly.inner.length; i<il; i++) {
+            bytes += polyRecordBytes(poly.inner[i]);
+        }
+    }
+    return bytes;
+}
+
 // legacy JS-only rasterizer uses OffscreenCanvas
 function renderLayer(params) {
     let {width, height, index, widgets, scaleX, scaleY} = params;
diff --git a/src/wasm/makefile b/src/wasm/makefile
index a60f7d82..4f4d279d 100644
--- a/src/wasm/makefile
+++ b/src/wasm/makefile
@@ -1,7 +1,7 @@
 all: kiri-sla.wasm kiri-geo.wasm kiri-ani.wasm
 
 kiri-sla.wasm: kiri-sla.c
-	emcc --no-entry -o kiri-sla.wasm kiri-sla.c -O3 -s ERROR_ON_UNDEFINED_SYMBOLS=0 -s TOTAL_MEMORY=40mb
+	emcc --no-entry -o kiri-sla.wasm kiri-sla.c -O3 -s ERROR_ON_UNDEFINED_SYMBOLS=0 -s INITIAL_MEMORY=64mb -s ALLOW_MEMORY_GROWTH=1
 
 kiri-geo.wasm: kiri-geo.cpp
 	emcc --no-entry -o kiri-geo.wasm clipper.cpp kiri-geo.cpp -Oz -s ERROR_ON_UNDEFINED_SYMBOLS=0 -s TOTAL_MEMORY=40mb